diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
index dd2d2911..5255a3cb 100644
--- a/.github/workflows/benchmarks.yml
+++ b/.github/workflows/benchmarks.yml
@@ -20,8 +20,7 @@ jobs:
       - uses: VirtusLab/scala-cli-setup@v0.1.20
         with:
           jvm: temurin:1.${{ matrix.jvm }}
-          apps: mill
-      - run: mill j${{ matrix.jvm }}.benchmarks.test -f1 -wi 2 -i 2 -o j${{ matrix.jvm }}-${{ matrix.os }}.bench -rff j${{ matrix.jvm }}-${{ matrix.os }}.json -rf json .*${{ matrix.benchmark }}${{ matrix.jit }}.*
+      - run: ./mill j${{ matrix.jvm }}.benchmarks.test -f1 -wi 2 -i 2 -o j${{ matrix.jvm }}-${{ matrix.os }}.bench -rff j${{ matrix.jvm }}-${{ matrix.os }}.json -rf json .*${{ matrix.benchmark }}${{ matrix.jit }}.*
       - run: scala-cli run scripts/PublishBenchmarkReport.sc -- "Java ${{ matrix.jvm}}" ${{ matrix.os }} out/j${{ matrix.jvm }}/benchmarks/test/jmhRun.dest/j${{ matrix.jvm }}-${{ matrix.os }}.json ${{ matrix.benchmark }} ${{ matrix.jit }} >> $GITHUB_STEP_SUMMARY
       - uses: actions/upload-artifact@v3
         with:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bdb4452d..2f97d45e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,8 +15,7 @@ jobs:
       - uses: coursier/setup-action@v1.3.0
         with:
           jvm: temurin:1.17
-          apps: mill
-      - run: mill mill.scalalib.scalafmt.ScalafmtModule/checkFormatAll __.sources
+      - run: ./mill mill.scalalib.scalafmt.ScalafmtModule/checkFormatAll __.sources
 
   unit-tests:
     strategy: 
diff --git a/build.sc b/build.sc
index 38dba93e..cde30743 100644
--- a/build.sc
+++ b/build.sc
@@ -16,7 +16,7 @@ trait BaseModule extends ScoverageModule with ScalafmtModule {
   def scalaVersion = "3.3.0"
   def scoverageVersion = "2.0.7"
 
-  val munitVersion = "1.0.0-M7"
+  val munitVersion = "1.0.0-M8"
   val jmhV = "1.33"
 
   def ivyDeps = Agg(
diff --git a/core/src/fr/hammons/slinc/Allocator.scala b/core/src/fr/hammons/slinc/Allocator.scala
index 5c8835a3..a7f39586 100644
--- a/core/src/fr/hammons/slinc/Allocator.scala
+++ b/core/src/fr/hammons/slinc/Allocator.scala
@@ -4,7 +4,7 @@ import java.lang.invoke.{MethodHandle, MethodType, MethodHandles}
 import fr.hammons.slinc.modules.DescriptorModule
 
 trait Allocator:
-  def allocate(descriptor: TypeDescriptor, num: Int): Mem
+  def allocate(descriptor: ForeignTypeDescriptor, num: Int): Mem
   def addCloseAction(fn: () => Unit): Unit
   def upcall[Fn](descriptor: FunctionDescriptor, target: Fn): Mem
   protected def methodHandleFromFn[Fn](
diff --git a/core/src/fr/hammons/slinc/CUnion.scala b/core/src/fr/hammons/slinc/CUnion.scala
index aacff1f3..5b885bc7 100644
--- a/core/src/fr/hammons/slinc/CUnion.scala
+++ b/core/src/fr/hammons/slinc/CUnion.scala
@@ -32,11 +32,12 @@ class CUnion[T <: Tuple](private[slinc] val mem: Mem):
     setHelper[T, A](a)
 
 object CUnion:
-  private inline def applyHelper[T <: Tuple](td: TypeDescriptor | Null)(using
-      DescriptorModule
-  ): TypeDescriptor = inline erasedValue[T] match
+  private inline def applyHelper[T <: Tuple](td: ForeignTypeDescriptor | Null)(
+      using DescriptorModule
+  ): ForeignTypeDescriptor = inline erasedValue[T] match
     case _: (a *: t) =>
-      val aDesc = summonInline[DescriptorOf[a]].descriptor
+      val aDesc =
+        summonInline[DescriptorOf[a]].descriptor.toForeignTypeDescriptor
       val max =
         if td != null then
           if td.size > aDesc.size then td
diff --git a/core/src/fr/hammons/slinc/DescriptorOf.scala b/core/src/fr/hammons/slinc/DescriptorOf.scala
index e94c7cec..eb7f5f71 100644
--- a/core/src/fr/hammons/slinc/DescriptorOf.scala
+++ b/core/src/fr/hammons/slinc/DescriptorOf.scala
@@ -58,6 +58,8 @@ object DescriptorOf:
   given DescriptorOf[VarArgs] with
     val descriptor: TypeDescriptor { type Inner = VarArgs } = VaListDescriptor
 
+  given [A](using t: Transform[A, ?]): DescriptorOf[A] = t
+
   def getDescriptorFor[A](using Quotes, Type[A]) =
     import quotes.reflect.*
     val expr = Expr
diff --git a/core/src/fr/hammons/slinc/FunctionDescriptor.scala b/core/src/fr/hammons/slinc/FunctionDescriptor.scala
index 6df6b9f2..089a36b2 100644
--- a/core/src/fr/hammons/slinc/FunctionDescriptor.scala
+++ b/core/src/fr/hammons/slinc/FunctionDescriptor.scala
@@ -23,8 +23,11 @@ final case class FunctionDescriptor(
       case FunctionDescriptor(head +: tail, variadicDescriptors, None) =>
         VoidHelper
           .methodTypeV(
-            head.toCarrierType,
-            tail.view.concat(variadicDescriptors).map(_.toCarrierType).toSeq*
+            head.toForeignTypeDescriptor.toCarrierType,
+            tail.view
+              .concat(variadicDescriptors)
+              .map(_.toForeignTypeDescriptor.toCarrierType)
+              .toSeq*
           )
           .nn
 
@@ -35,15 +38,20 @@ final case class FunctionDescriptor(
           ) =>
         MethodType
           .methodType(
-            outputDescriptor.toCarrierType,
-            head.toCarrierType,
-            tail.view.concat(variadicDescriptors).map(_.toCarrierType).toSeq*
+            outputDescriptor.toForeignTypeDescriptor.toCarrierType,
+            head.toForeignTypeDescriptor.toCarrierType,
+            tail.view
+              .concat(variadicDescriptors)
+              .map(_.toForeignTypeDescriptor.toCarrierType)
+              .toSeq*
           )
           .nn
 
       case FunctionDescriptor(_, _, None) => VoidHelper.methodTypeV().nn
       case FunctionDescriptor(_, _, Some(outputDescriptor)) =>
-        MethodType.methodType(outputDescriptor.toCarrierType).nn
+        MethodType
+          .methodType(outputDescriptor.toForeignTypeDescriptor.toCarrierType)
+          .nn
 
 object FunctionDescriptor:
   def fromDefDef(using q: Quotes)(symbol: q.reflect.Symbol) =
diff --git a/core/src/fr/hammons/slinc/Ptr.scala b/core/src/fr/hammons/slinc/Ptr.scala
index aab0bb26..c99dc3e3 100644
--- a/core/src/fr/hammons/slinc/Ptr.scala
+++ b/core/src/fr/hammons/slinc/Ptr.scala
@@ -29,14 +29,18 @@ class Ptr[A](private[slinc] val mem: Mem, private[slinc] val offset: Bytes):
       r: ReadWriteModule
   )(using ClassTag[A]): IArray[A] =
     IArray.unsafeFromArray(
-      r.readArray(mem.resize(DescriptorOf[A].size * size), offset, size)
+      r.readArray(
+        mem.resize(DescriptorOf[A].toForeignTypeDescriptor.size * size),
+        offset,
+        size
+      )
     )
 
   def `unary_!_=`(value: A)(using rwM: ReadWriteModule, desc: DescriptorOf[A]) =
     rwM.write(mem, offset, desc.descriptor, value)
   def apply(bytes: Bytes): Ptr[A] = Ptr[A](mem, offset + bytes)
   def apply(index: Int)(using DescriptorOf[A], DescriptorModule): Ptr[A] =
-    Ptr[A](mem, offset + (DescriptorOf[A].size * index))
+    Ptr[A](mem, offset + (DescriptorOf[A].toForeignTypeDescriptor.size * index))
 
   def castTo[A]: Ptr[A] = this.asInstanceOf[Ptr[A]]
   private[slinc] def resize(toBytes: Bytes) =
@@ -59,12 +63,15 @@ object Ptr:
   def blankArray[A](
       num: Int
   )(using descriptor: DescriptorOf[A], alloc: Allocator): Ptr[A] =
-    Ptr[A](alloc.allocate(DescriptorOf[A], num), Bytes(0))
+    Ptr[A](
+      alloc.allocate(DescriptorOf[A].toForeignTypeDescriptor, num),
+      Bytes(0)
+    )
 
   def copy[A](
       a: Array[A]
   )(using alloc: Allocator, descriptor: DescriptorOf[A], rwm: ReadWriteModule) =
-    val mem = alloc.allocate(DescriptorOf[A], a.size)
+    val mem = alloc.allocate(DescriptorOf[A].toForeignTypeDescriptor, a.size)
     rwm.writeArray(mem, Bytes(0), a)
     Ptr[A](mem, Bytes(0))
 
@@ -76,7 +83,7 @@ object Ptr:
         val descriptor: TypeDescriptor { type Inner = A }
       }
   ) =
-    val mem = alloc.allocate(DescriptorOf[A], 1)
+    val mem = alloc.allocate(DescriptorOf[A].toForeignTypeDescriptor, 1)
     rwm.write(mem, Bytes(0), descriptor.descriptor, a)
     Ptr[A](mem, Bytes(0))
 
diff --git a/core/src/fr/hammons/slinc/Slinc.scala b/core/src/fr/hammons/slinc/Slinc.scala
index c7577b6e..4d0a142b 100644
--- a/core/src/fr/hammons/slinc/Slinc.scala
+++ b/core/src/fr/hammons/slinc/Slinc.scala
@@ -22,7 +22,7 @@ trait Slinc:
   export types.os
 
   def sizeOf[A](using l: DescriptorOf[A]) =
-    SizeT.maybe(DescriptorOf[A].size.toLong).get
+    SizeT.maybe(DescriptorOf[A].toForeignTypeDescriptor.size.toLong).get
 
   def Null[A] = scopePlatformSpecific.nullPtr[A]
 
diff --git a/core/src/fr/hammons/slinc/Struct.scala b/core/src/fr/hammons/slinc/Struct.scala
index 89c32a88..761903d7 100644
--- a/core/src/fr/hammons/slinc/Struct.scala
+++ b/core/src/fr/hammons/slinc/Struct.scala
@@ -36,7 +36,8 @@ object Struct:
       rwm: ReadWriteModule,
       dm: DescriptorModule
   ): Writer[A] =
-    val offsets = dm.memberOffsets(memberDescriptors[A])
+    val offsets =
+      dm.memberOffsets(memberDescriptors[A].map(_.toForeignTypeDescriptor))
     (mem, offset, value) =>
       writeGenHelper(
         offsets.map(_ + offset),
@@ -67,7 +68,8 @@ object Struct:
       rwm: ReadWriteModule,
       dm: DescriptorModule
   ): Reader[A] =
-    val offsets: IArray[Bytes] = dm.memberOffsets(memberDescriptors[A])
+    val offsets: IArray[Bytes] =
+      dm.memberOffsets(memberDescriptors[A].map(_.toForeignTypeDescriptor))
     (mem, offset) => {
       val elems: m.MirroredElemTypes =
         readGenHelper[m.MirroredElemTypes](offsets.map(_ + offset), 0, mem)
diff --git a/core/src/fr/hammons/slinc/Transform.scala b/core/src/fr/hammons/slinc/Transform.scala
new file mode 100644
index 00000000..bc62875e
--- /dev/null
+++ b/core/src/fr/hammons/slinc/Transform.scala
@@ -0,0 +1,13 @@
+package fr.hammons.slinc
+
+trait Transform[A, B](using val desc: DescriptorOf[B])(
+    _transformFrom: B => A,
+    _transformTo: A => B
+) extends DescriptorOf[A]:
+  val descriptor
+      : TransformDescriptor { type Inner = A; val cRep: desc.descriptor.type } =
+    new TransformDescriptor:
+      val cRep: desc.descriptor.type = desc.descriptor
+      type Inner = A
+      val transformFrom = _transformFrom
+      val transformTo = _transformTo
diff --git a/core/src/fr/hammons/slinc/TypeDescriptor.scala b/core/src/fr/hammons/slinc/TypeDescriptor.scala
index 38ab3e13..117bebb1 100644
--- a/core/src/fr/hammons/slinc/TypeDescriptor.scala
+++ b/core/src/fr/hammons/slinc/TypeDescriptor.scala
@@ -22,10 +22,6 @@ sealed trait TypeDescriptor:
   type Inner
   given DescriptorOf[Inner] with
     val descriptor = self
-  def size(using dm: DescriptorModule): Bytes = dm.sizeOf(this)
-  def alignment(using dm: DescriptorModule): Bytes = dm.alignmentOf(this)
-  def toCarrierType(using dm: DescriptorModule): Class[?] =
-    dm.toCarrierType(this)
 
   val reader: (ReadWriteModule, DescriptorModule) ?=> Reader[Inner]
   val writer: (ReadWriteModule, DescriptorModule) ?=> Writer[Inner]
@@ -44,7 +40,7 @@ sealed trait TypeDescriptor:
         Inner
       ] =
     val reader = this.reader
-    val size = this.size
+    val size = this.toForeignTypeDescriptor.size
     (mem, offset, num) => {
       var i = 0
       val array = Array.ofDim[Inner](num)
@@ -57,12 +53,22 @@ sealed trait TypeDescriptor:
   val arrayWriter
       : (ReadWriteModule, DescriptorModule) ?=> Writer[Array[Inner]] =
     val writer = this.writer
-    val size = this.size
+    val size = this.toForeignTypeDescriptor.size
     (mem, offset, a) =>
       var i = 0
       while i < a.length do
         writer(mem, size * i + offset, a(i))
         i += 1
+
+  def toForeignTypeDescriptor: ForeignTypeDescriptor
+
+sealed trait ForeignTypeDescriptor extends TypeDescriptor:
+  def toForeignTypeDescriptor: ForeignTypeDescriptor = this
+  def size(using dm: DescriptorModule): Bytes = dm.sizeOf(this)
+  def alignment(using dm: DescriptorModule): Bytes = dm.alignmentOf(this)
+  def toCarrierType(using dm: DescriptorModule): Class[?] =
+    dm.toCarrierType(this)
+
 object TypeDescriptor:
   def fromTypeRepr(using q: Quotes)(
       typeRepr: q.reflect.TypeRepr
@@ -83,7 +89,7 @@ object TypeDescriptor:
 
   inline val unusedImplicit = "msg=unused implicit parameter"
 
-sealed trait BasicDescriptor extends TypeDescriptor:
+sealed trait BasicDescriptor extends ForeignTypeDescriptor:
   override val argumentTransition = identity
 
   override val returnTransition = _.asInstanceOf[Inner]
@@ -118,7 +124,7 @@ case object DoubleDescriptor extends BasicDescriptor:
   val reader = readWriteModule.doubleReader
   val writer = readWriteModule.doubleWriter
 
-case object PtrDescriptor extends TypeDescriptor:
+case object PtrDescriptor extends ForeignTypeDescriptor:
   type Inner = Ptr[?]
   override val reader = (mem, offset) =>
     Ptr(readWriteModule.memReader(mem, offset), Bytes(0))
@@ -152,7 +158,7 @@ trait StructDescriptor(
     val members: List[StructMemberDescriptor],
     val clazz: Class[?],
     val transform: Tuple => Product
-) extends TypeDescriptor
+) extends ForeignTypeDescriptor
 
 case class AliasDescriptor[A](val real: TypeDescriptor) extends TypeDescriptor:
   type Inner = A
@@ -174,13 +180,11 @@ case class AliasDescriptor[A](val real: TypeDescriptor) extends TypeDescriptor:
     summon[TransitionModule].methodArgument(real, _, summon[Allocator])
 
   override val returnTransition = summon[TransitionModule].methodReturn(real, _)
-  override def size(using dm: DescriptorModule): Bytes = dm.sizeOf(real)
-  override def alignment(using dm: DescriptorModule): Bytes =
-    dm.alignmentOf(real)
-  override def toCarrierType(using dm: DescriptorModule): Class[?] =
-    dm.toCarrierType(real)
 
-case object VaListDescriptor extends TypeDescriptor:
+  def toForeignTypeDescriptor: ForeignTypeDescriptor =
+    real.toForeignTypeDescriptor
+
+case object VaListDescriptor extends ForeignTypeDescriptor:
   type Inner = VarArgs
 
   override val reader: (ReadWriteModule, DescriptorModule) ?=> Reader[Inner] =
@@ -200,7 +204,7 @@ case object VaListDescriptor extends TypeDescriptor:
     summon[TransitionModule].addressReturn(o).asVarArgs
 
 case class CUnionDescriptor(possibleTypes: Set[TypeDescriptor])
-    extends TypeDescriptor:
+    extends ForeignTypeDescriptor:
   type Inner = CUnion[? <: NonEmptyTuple]
 
   override val reader: (ReadWriteModule, DescriptorModule) ?=> Reader[Inner] =
@@ -223,7 +227,7 @@ case class SetSizeArrayDescriptor(
     val contained: TypeDescriptor,
     val number: Int
 )(using ClassTag[contained.Inner])
-    extends TypeDescriptor:
+    extends ForeignTypeDescriptor:
 
   override val reader: (ReadWriteModule, DescriptorModule) ?=> Reader[Inner] =
     (mem, offset) =>
@@ -256,3 +260,32 @@ case class SetSizeArrayDescriptor(
       summon[ReadWriteModule].read(mem, Bytes(0), this)
 
   type Inner = SetSizeArray[contained.Inner, ?]
+
+trait TransformDescriptor extends TypeDescriptor:
+  val cRep: TypeDescriptor
+  val transformTo: Inner => cRep.Inner
+  val transformFrom: cRep.Inner => Inner
+
+  protected inline def toInner[A <: Matchable](a: A) =
+    import scala.compiletime.error
+    inline a match
+      case b: cRep.Inner => b
+      case _             => error("cannot convert")
+
+  override val reader: (ReadWriteModule, DescriptorModule) ?=> Reader[Inner] =
+    (mem: Mem, bytes: Bytes) => transformFrom(cRep.reader(mem, bytes))
+
+  override val writer: (ReadWriteModule, DescriptorModule) ?=> Writer[Inner] =
+    (mem, bytes, value) => cRep.writer(mem, bytes, transformTo(value))
+
+  override val argumentTransition
+      : (TransitionModule, ReadWriteModule, Allocator) ?=> ArgumentTransition[
+        Inner
+      ] = cRep.argumentTransition.compose(transformTo)
+
+  override val returnTransition
+      : (TransitionModule, ReadWriteModule) ?=> ReturnTransition[Inner] =
+    cRep.returnTransition.andThen(transformFrom)
+
+  def toForeignTypeDescriptor: ForeignTypeDescriptor =
+    cRep.toForeignTypeDescriptor
diff --git a/core/src/fr/hammons/slinc/modules/DescriptorModule.scala b/core/src/fr/hammons/slinc/modules/DescriptorModule.scala
index ea467972..75b44fa4 100644
--- a/core/src/fr/hammons/slinc/modules/DescriptorModule.scala
+++ b/core/src/fr/hammons/slinc/modules/DescriptorModule.scala
@@ -1,11 +1,12 @@
 package fr.hammons.slinc.modules
 
-import fr.hammons.slinc.{Bytes, TypeDescriptor}
+import fr.hammons.slinc.Bytes
+import fr.hammons.slinc.ForeignTypeDescriptor
 
 /** A module used to perform Platform dependent work with a descriptor
   */
 trait DescriptorModule:
-  def memberOffsets(sd: List[TypeDescriptor]): IArray[Bytes]
-  def sizeOf(td: TypeDescriptor): Bytes
-  def alignmentOf(td: TypeDescriptor): Bytes
-  def toCarrierType(td: TypeDescriptor): Class[?]
+  def memberOffsets(sd: List[ForeignTypeDescriptor]): IArray[Bytes]
+  def sizeOf(td: ForeignTypeDescriptor): Bytes
+  def alignmentOf(td: ForeignTypeDescriptor): Bytes
+  def toCarrierType(td: ForeignTypeDescriptor): Class[?]
diff --git a/core/src/fr/hammons/slinc/types/Basic.scala b/core/src/fr/hammons/slinc/types/Basic.scala
index 1d8e81ad..e4d46218 100644
--- a/core/src/fr/hammons/slinc/types/Basic.scala
+++ b/core/src/fr/hammons/slinc/types/Basic.scala
@@ -1,8 +1,26 @@
 package fr.hammons.slinc.types
 
+import fr.hammons.slinc.Transform
+
 type CChar = Byte
 type CShort = Short
 type CInt = Int
 type CFloat = Float
 type CDouble = Double
 type CLongLong = Long
+
+opaque type CBool >: Boolean <: Boolean = Boolean
+
+object CBool:
+  given Transform[CBool, Byte](
+    b => if b != (0: Byte) then true else false,
+    b => if b then 1: Byte else 0: Byte
+  )
+
+opaque type CBoolShort >: Boolean <: Boolean = Boolean
+
+object CBoolShort:
+  given Transform[CBoolShort, Short](
+    s => if s != (0: Short) then true else false,
+    b => if b then 1: Short else 0: Short
+  )
diff --git a/core/test/native/test.c b/core/test/native/test.c
deleted file mode 100644
index 53154f83..00000000
--- a/core/test/native/test.c
+++ /dev/null
@@ -1,174 +0,0 @@
-#include <stdlib.h>
-#include <ctype.h>
-#include <stdarg.h>
-#include <stdio.h>
-
-struct a_t
-{
-   int a;
-   int b;
-};
-
-struct b_t
-{
-   int c;
-   struct a_t d;
-};
-
-struct c_t
-{
-   int a[3];
-   float b[3];
-};
-
-int int_test(int a)
-{
-   return a + 3;
-}
-
-short short_test(short a)
-{
-   return a + 2;
-}
-
-char byte_test(char a)
-{
-   return a + 1;
-}
-
-char char_test(char a)
-{
-   return toupper(a);
-}
-
-long long_test(long a)
-{
-   return a + 4;
-}
-
-float float_test(float a)
-{
-   return a + 4.0f;
-}
-
-double double_test(double a)
-{
-   return a + 3.0;
-}
-
-int bool_test(int a)
-{
-   if (a)
-   {
-      return !a;
-   }
-   else
-   {
-      return a;
-   }
-}
-
-char string_test(char *str)
-{
-   return str[1];
-}
-
-char *badval;
-
-void bad_method(const char *str)
-{
-   badval = str;
-   return;
-}
-
-char *ibreak(char *str)
-{
-   return badval;
-}
-
-int sum(int n, ...)
-{
-   int Sum = 0;
-   va_list ptr;
-   va_start(ptr, n);
-   for (int i = 0; i < n; i++)
-      Sum += va_arg(ptr, int);
-
-   va_end(ptr);
-
-   return Sum;
-}
-
-struct b_t slinc_test_modify(struct b_t b)
-{
-   b.d.a += 6;
-   return b;
-}
-
-struct c_t slinc_test_addone(struct c_t c)
-{
-   for (int i = 0; i < 3; i++)
-   {
-      c.a[i] += 1;
-      c.b[i] += 1;
-   }
-
-   return c;
-}
-
-void slinc_test_passstaticarr(int res[3])
-{
-   return;
-}
-
-int *slinc_test_getstaticarr()
-{
-
-   int *ret = malloc(sizeof(int) * 3);
-   ret[0] = 1;
-   ret[1] = 2;
-   ret[2] = 3;
-
-   return ret;
-}
-
-int slinc_two_structs(struct a_t a, struct a_t b)
-{
-   return a.a * b.a;
-}
-
-int slinc_upcall(int (*zptr)())
-{
-   return zptr();
-}
-
-int slinc_upcall_a_t(struct a_t (*zptr)())
-{
-   struct a_t a = zptr();
-   return a.a + a.b;
-}
-
-struct a_t get_a_struct()
-{
-   struct a_t a;
-   a.a = 3;
-   a.b = 2;
-   return a;
-}
-
-typedef struct a_t (*a_fn_ptr)();
-a_fn_ptr slinc_fptr_ret()
-{
-   return get_a_struct;
-}
-
-int adder(int a, int b)
-{
-   return a + b;
-}
-
-typedef int (*adderfn)(int, int);
-adderfn slinc_fptr_ret2()
-{
-   return adder;
-}
diff --git a/core/test/resources/native/test.c b/core/test/resources/native/test.c
index 8a7543a7..f4d9e30b 100644
--- a/core/test/resources/native/test.c
+++ b/core/test/resources/native/test.c
@@ -147,4 +147,8 @@ EXPORTED int* i180_test(int my_array[5]) {
     i++;
   }
   return my_array;
+}
+
+EXPORTED char i213_test(char bool) {
+  return bool;
 }
\ No newline at end of file
diff --git a/core/test/src/fr/hammons/slinc/BindingSpec.scala b/core/test/src/fr/hammons/slinc/BindingSpec.scala
index 45df3fe3..3502798f 100644
--- a/core/test/src/fr/hammons/slinc/BindingSpec.scala
+++ b/core/test/src/fr/hammons/slinc/BindingSpec.scala
@@ -63,6 +63,8 @@ trait BindingSpec(val slinc: Slinc) extends ScalaCheckSuite:
         input: SetSizeArray[CInt, 5]
     ): SetSizeArray[CInt, 5]
 
+    def i213_test(b: CBool): CBool
+
   test("int_identity") {
     val test = FSet.instance[TestLib]
 
@@ -198,3 +200,8 @@ trait BindingSpec(val slinc: Slinc) extends ScalaCheckSuite:
         val retArr = test.i180_test(arr)
 
         retArr.zip(arr.map(_ * 2)).foreach(assertEquals(_, _))
+
+  property("issue 213 - can send and receive boolean values"):
+      val test = FSet.instance[TestLib]
+      forAll: (b: Boolean) =>
+        assertEquals(test.i213_test(b), b)
diff --git a/core/test/src/fr/hammons/slinc/StdlibSpec.scala b/core/test/src/fr/hammons/slinc/StdlibSpec.scala
index 860b092c..30ef9016 100644
--- a/core/test/src/fr/hammons/slinc/StdlibSpec.scala
+++ b/core/test/src/fr/hammons/slinc/StdlibSpec.scala
@@ -110,7 +110,7 @@ trait StdlibSpec(val slinc: Slinc) extends ScalaCheckSuite:
                 cstd.qsort(
                   cArr,
                   len,
-                  DescriptorOf[Int].size.toSizeT,
+                  DescriptorOf[CInt].toForeignTypeDescriptor.size.toSizeT,
                   Ptr.upcall((a: Ptr[Nothing], b: Ptr[Nothing]) =>
                     val aVal = !a.castTo[CInt]
                     val bVal = !b.castTo[CInt]
@@ -136,7 +136,7 @@ trait StdlibSpec(val slinc: Slinc) extends ScalaCheckSuite:
         cstd.qsort(
           arr,
           size,
-          DescriptorOf[CInt].size.toSizeT,
+          DescriptorOf[CInt].toForeignTypeDescriptor.size.toSizeT,
           Ptr.upcall: (a, b) =>
             val aVal = !a.castTo[CInt]
             val bVal = !b.castTo[CInt]
diff --git a/core/test/src/fr/hammons/slinc/TypeDescriptorSpec.scala b/core/test/src/fr/hammons/slinc/TypeDescriptorSpec.scala
index 72717863..b7b3f28d 100644
--- a/core/test/src/fr/hammons/slinc/TypeDescriptorSpec.scala
+++ b/core/test/src/fr/hammons/slinc/TypeDescriptorSpec.scala
@@ -25,3 +25,25 @@ class TypeDescriptorSpec extends munit.FunSuite:
           )
         ): TypeDescriptor
       )
+
+  test("Transforms work in place of DescriptorOfs"):
+      val result = compileErrors(
+        """
+        import fr.hammons.slinc.types.*
+        
+        trait Test derives FSet{
+        def test(a: CBool): CBool
+        def test2(a: CBoolShort): CBoolShort
+        }
+
+        val runtime: Slinc = ???
+
+        import runtime.{*,given}
+        val test = FSet.instance[Test]
+
+        val bool: Boolean = test.test(true)
+        val bool2: Boolean = test.test2(true)
+      """
+      )
+
+      assertNoDiff(result, "")
diff --git a/core/test/src/fr/hammons/slinc/TypesSpec.scala b/core/test/src/fr/hammons/slinc/TypesSpec.scala
index f49e1ec9..3a5423b8 100644
--- a/core/test/src/fr/hammons/slinc/TypesSpec.scala
+++ b/core/test/src/fr/hammons/slinc/TypesSpec.scala
@@ -6,7 +6,7 @@ import types.*
 trait TypesSpec(val slinc: Slinc) extends munit.FunSuite:
   import slinc.{*, given}
   test("can create maximally sized CLongs") {
-    val size = DescriptorOf[CLong].size
+    val size = DescriptorOf[CLong].toForeignTypeDescriptor.size
     val x =
       if size == 4.toBytes then Some(CLong(Int.MaxValue))
       else if size == 8.toBytes then CLong.maybe(Long.MaxValue)
diff --git a/core/test/src/fr/hammons/slinc/modules/DescriptorSpec.scala b/core/test/src/fr/hammons/slinc/modules/DescriptorSpec.scala
index 2519844d..8d9d9089 100644
--- a/core/test/src/fr/hammons/slinc/modules/DescriptorSpec.scala
+++ b/core/test/src/fr/hammons/slinc/modules/DescriptorSpec.scala
@@ -22,14 +22,16 @@ trait DescriptorSpec(val slinc: Slinc) extends munit.FunSuite:
       derives Struct
   test("CUnionDescriptor.size gives the right size"):
       assertEquals(
-        DescriptorOf[CUnion[(CInt, A, CFloat)]].size,
-        DescriptorOf[A].size
+        DescriptorOf[CUnion[(CInt, A, CFloat)]].toForeignTypeDescriptor.size,
+        DescriptorOf[A].toForeignTypeDescriptor.size
       )
 
   test("CUnionDescriptor.alignment gives the right alignment"):
       assertEquals(
-        DescriptorOf[CUnion[(CInt, A, CFloat)]].alignment,
-        DescriptorOf[A].alignment
+        DescriptorOf[
+          CUnion[(CInt, A, CFloat)]
+        ].toForeignTypeDescriptor.alignment,
+        DescriptorOf[A].toForeignTypeDescriptor.alignment
       )
 
   test("ByteDescriptor is 1 byte in size"):
@@ -51,25 +53,32 @@ trait DescriptorSpec(val slinc: Slinc) extends munit.FunSuite:
       assertEquals(DoubleDescriptor.size, Bytes(8))
 
   test("StructDescriptor.alignment is the max of the member elements"):
-      assertEquals(DescriptorOf[A].alignment, Bytes(8))
+      assertEquals(DescriptorOf[A].toForeignTypeDescriptor.alignment, Bytes(8))
 
   test("StructDescriptor.size is a multiple of alignment"):
 
-      assertEquals(DescriptorOf[A].size % DescriptorOf[A].alignment, Bytes(0))
+      assertEquals(
+        DescriptorOf[A].toForeignTypeDescriptor.size % DescriptorOf[
+          A
+        ].toForeignTypeDescriptor.alignment,
+        Bytes(0)
+      )
       assert(
-        DescriptorOf[A].size >= (DescriptorOf[CInt].size * 3 + DescriptorOf[
+        DescriptorOf[A].toForeignTypeDescriptor.size >= (DescriptorOf[
+          CInt
+        ].toForeignTypeDescriptor.size * 3 + DescriptorOf[
           CLongLong
-        ].size * 2)
+        ].toForeignTypeDescriptor.size * 2)
       )
 
   test("SetSizeArrayDescriptor is size of inner type * num"):
       assertEquals(
-        DescriptorOf[SetSizeArray[CInt, 15]].size,
-        DescriptorOf[CInt].size * 15
+        DescriptorOf[SetSizeArray[CInt, 15]].toForeignTypeDescriptor.size,
+        DescriptorOf[CInt].toForeignTypeDescriptor.size * 15
       )
 
   test("SetSizeArrayDescriptor is alignment of inner type"):
       assertEquals(
-        DescriptorOf[SetSizeArray[CInt, 15]].alignment,
-        DescriptorOf[CInt].alignment
+        DescriptorOf[SetSizeArray[CInt, 15]].toForeignTypeDescriptor.alignment,
+        DescriptorOf[CInt].toForeignTypeDescriptor.alignment
       )
diff --git a/j17/src/fr/hammons/slinc/Allocator17.scala b/j17/src/fr/hammons/slinc/Allocator17.scala
index 868800fe..2bb57dc6 100644
--- a/j17/src/fr/hammons/slinc/Allocator17.scala
+++ b/j17/src/fr/hammons/slinc/Allocator17.scala
@@ -63,7 +63,7 @@ class Allocator17(
         .nn
     )
 
-  override def allocate(descriptor: TypeDescriptor, num: Int): Mem =
+  override def allocate(descriptor: ForeignTypeDescriptor, num: Int): Mem =
     Mem17(
       segmentAllocator
         .allocate(descriptor.size.toLong * num, descriptor.alignment.toLong)
diff --git a/j17/src/fr/hammons/slinc/InferredAllocator17.scala b/j17/src/fr/hammons/slinc/InferredAllocator17.scala
index 60dfd15b..d6f5727f 100644
--- a/j17/src/fr/hammons/slinc/InferredAllocator17.scala
+++ b/j17/src/fr/hammons/slinc/InferredAllocator17.scala
@@ -50,7 +50,7 @@ class InferredAllocator17(scope: ResourceScope, linker: CLinker)
         if allocated.isEmpty then scope.close()
     )
 
-  override def allocate(descriptor: TypeDescriptor, num: Int): Mem =
+  override def allocate(descriptor: ForeignTypeDescriptor, num: Int): Mem =
     val mem = Mem17(
       allocator
         .allocate(
diff --git a/j17/src/fr/hammons/slinc/VarArgs17.scala b/j17/src/fr/hammons/slinc/VarArgs17.scala
index ebefb848..83b5d484 100644
--- a/j17/src/fr/hammons/slinc/VarArgs17.scala
+++ b/j17/src/fr/hammons/slinc/VarArgs17.scala
@@ -14,7 +14,7 @@ import scala.util.chaining.*
 
 class VarArgs17(args: VaList) extends VarArgs:
   private def get(td: TypeDescriptor): Object =
-    td match
+    td.toForeignTypeDescriptor match
       case ByteDescriptor   => Byte.box(args.vargAsInt(C_INT).toByte)
       case ShortDescriptor  => Short.box(args.vargAsInt(C_INT).toShort)
       case IntDescriptor    => Int.box(args.vargAsInt(C_INT))
@@ -32,7 +32,6 @@ class VarArgs17(args: VaList) extends VarArgs:
             )
             .nn
         )
-      case AliasDescriptor(real) => get(real)
       case cud: CUnionDescriptor =>
         LinkageModule17.tempScope(alloc ?=>
           args
@@ -46,7 +45,7 @@ class VarArgs17(args: VaList) extends VarArgs:
     transitionModule17.methodReturn[A](d.descriptor, get(d.descriptor))
 
   private def skip(td: TypeDescriptor): Unit =
-    td match
+    td.toForeignTypeDescriptor match
       case ByteDescriptor                            => args.skip(C_INT)
       case ShortDescriptor                           => args.skip(C_INT)
       case IntDescriptor                             => args.skip(C_INT)
@@ -56,8 +55,7 @@ class VarArgs17(args: VaList) extends VarArgs:
       case PtrDescriptor | _: SetSizeArrayDescriptor => args.skip(C_POINTER)
       case sd: StructDescriptor =>
         args.skip(descriptorModule17.toGroupLayout(sd))
-      case AliasDescriptor(real) => skip(real)
-      case VaListDescriptor      => args.skip(C_POINTER)
+      case VaListDescriptor => args.skip(C_POINTER)
       case cud: CUnionDescriptor =>
         args.skip(descriptorModule17.toMemoryLayout(cud))
 
diff --git a/j17/src/fr/hammons/slinc/modules/DescriptorModule17.scala b/j17/src/fr/hammons/slinc/modules/DescriptorModule17.scala
index 7ab52be5..f6b535c0 100644
--- a/j17/src/fr/hammons/slinc/modules/DescriptorModule17.scala
+++ b/j17/src/fr/hammons/slinc/modules/DescriptorModule17.scala
@@ -19,7 +19,7 @@ given descriptorModule17: DescriptorModule with
   val chm: TrieMap[StructDescriptor, GroupLayout] = TrieMap.empty
   val offsets: TrieMap[List[TypeDescriptor], IArray[Bytes]] = TrieMap.empty
 
-  def toCarrierType(td: TypeDescriptor): Class[?] = td match
+  override def toCarrierType(td: ForeignTypeDescriptor): Class[?] = td match
     case ByteDescriptor   => classOf[Byte]
     case ShortDescriptor  => classOf[Short]
     case IntDescriptor    => classOf[Int]
@@ -30,7 +30,6 @@ given descriptorModule17: DescriptorModule with
     case _: StructDescriptor | _: CUnionDescriptor =>
       classOf[MemorySegment]
     case VaListDescriptor | _: SetSizeArrayDescriptor => classOf[MemoryAddress]
-    case ad: AliasDescriptor[?]                       => toCarrierType(ad.real)
 
   def genLayoutList(
       layouts: Seq[MemoryLayout],
@@ -64,15 +63,15 @@ given descriptorModule17: DescriptorModule with
       else Seq.empty
     )
 
-  override def sizeOf(td: TypeDescriptor): Bytes = Bytes(
+  override def sizeOf(td: ForeignTypeDescriptor): Bytes = Bytes(
     toMemoryLayout(td).byteSize()
   )
 
-  override def alignmentOf(td: TypeDescriptor): Bytes = Bytes(
+  override def alignmentOf(td: ForeignTypeDescriptor): Bytes = Bytes(
     toMemoryLayout(td).byteAlignment
   )
 
-  override def memberOffsets(sd: List[TypeDescriptor]): IArray[Bytes] =
+  override def memberOffsets(sd: List[ForeignTypeDescriptor]): IArray[Bytes] =
     offsets.getOrElseUpdate(
       sd, {
         val ll = genLayoutList(
@@ -108,16 +107,17 @@ given descriptorModule17: DescriptorModule with
     case _                         => throw Error("Unsupported platform!")
 
   def toMemoryLayout(td: TypeDescriptor): MemoryLayout = td match
-    case ByteDescriptor         => platform.jByte
-    case ShortDescriptor        => platform.jShort
-    case IntDescriptor          => platform.jInt
-    case LongDescriptor         => platform.jLong
-    case FloatDescriptor        => platform.jFloat
-    case DoubleDescriptor       => platform.jDouble
-    case PtrDescriptor          => C_POINTER.nn
-    case VaListDescriptor       => C_POINTER.nn
-    case sd: StructDescriptor   => toGroupLayout(sd)
-    case ad: AliasDescriptor[?] => toMemoryLayout(ad.real)
+    case ByteDescriptor          => platform.jByte
+    case ShortDescriptor         => platform.jShort
+    case IntDescriptor           => platform.jInt
+    case LongDescriptor          => platform.jLong
+    case FloatDescriptor         => platform.jFloat
+    case DoubleDescriptor        => platform.jDouble
+    case PtrDescriptor           => C_POINTER.nn
+    case VaListDescriptor        => C_POINTER.nn
+    case sd: StructDescriptor    => toGroupLayout(sd)
+    case ad: AliasDescriptor[?]  => toMemoryLayout(ad.real)
+    case td: TransformDescriptor => toMemoryLayout(td.cRep)
     case SetSizeArrayDescriptor(inner, num) =>
       MemoryLayout.sequenceLayout(num, toMemoryLayout(inner)).nn
     case CUnionDescriptor(possibleTypes) =>
diff --git a/j17/src/fr/hammons/slinc/modules/LinkageModule17.scala b/j17/src/fr/hammons/slinc/modules/LinkageModule17.scala
index 5ed0d1b4..8e81e12d 100644
--- a/j17/src/fr/hammons/slinc/modules/LinkageModule17.scala
+++ b/j17/src/fr/hammons/slinc/modules/LinkageModule17.scala
@@ -36,7 +36,9 @@ object LinkageModule17 extends LinkageModule:
     )
 
     val mtConstructor = (carriers: Seq[Class[?]]) =>
-      descriptor.returnDescriptor.map(toCarrierType) match
+      descriptor.returnDescriptor
+        .map(_.toForeignTypeDescriptor)
+        .map(toCarrierType) match
         case None =>
           carriers match
             case head +: tail =>
@@ -53,6 +55,7 @@ object LinkageModule17 extends LinkageModule:
     val mt = mtConstructor(
       descriptor.inputDescriptors.view
         .concat(variadicDescriptors)
+        .map(_.toForeignTypeDescriptor)
         .map(toCarrierType)
         .toSeq
     )
diff --git a/j17/src/fr/hammons/slinc/modules/ReadWriteModule17.scala b/j17/src/fr/hammons/slinc/modules/ReadWriteModule17.scala
index 6b9c81f2..b97ea5c3 100644
--- a/j17/src/fr/hammons/slinc/modules/ReadWriteModule17.scala
+++ b/j17/src/fr/hammons/slinc/modules/ReadWriteModule17.scala
@@ -42,20 +42,22 @@ given readWriteModule17: ReadWriteModule with
 
   val memReader = (mem, offset) => mem.readAddress(offset)
 
-  def unionReader(
+  override def unionReader(
       typeDescriptor: TypeDescriptor
   ): Reader[CUnion[? <: NonEmptyTuple]] =
-    val size = descriptorModule17.sizeOf(typeDescriptor)
+    val size = descriptorModule17.sizeOf(typeDescriptor.toForeignTypeDescriptor)
     (mem, offset) =>
       Scope17.createInferredScope(alloc ?=>
-        val newMem = alloc.allocate(typeDescriptor, 1)
+        val newMem = alloc.allocate(typeDescriptor.toForeignTypeDescriptor, 1)
         newMem.copyFrom(mem.offset(offset).resize(size))
 
         new CUnion(newMem)
       )
 
-  def unionWriter(td: TypeDescriptor): Writer[CUnion[? <: NonEmptyTuple]] =
-    val size = descriptorModule17.sizeOf(td)
+  override def unionWriter(
+      td: TypeDescriptor
+  ): Writer[CUnion[? <: NonEmptyTuple]] =
+    val size = descriptorModule17.sizeOf(td.toForeignTypeDescriptor)
     (mem, offset, value) => mem.offset(offset).resize(size).copyFrom(value.mem)
 
   arrayWriterCache
diff --git a/j19/src/fr/hammons/slinc/Allocator19.scala b/j19/src/fr/hammons/slinc/Allocator19.scala
index c46dc9b2..dde7ab26 100644
--- a/j19/src/fr/hammons/slinc/Allocator19.scala
+++ b/j19/src/fr/hammons/slinc/Allocator19.scala
@@ -30,14 +30,16 @@ class Allocator19(
     val fd = descriptor.outputDescriptor match
       case Some(r) =>
         JFunctionDescriptor.of(
-          descriptorModule19.toMemoryLayout(r),
+          descriptorModule19.toMemoryLayout(r.toForeignTypeDescriptor),
           descriptor.inputDescriptors.view
+            .map(_.toForeignTypeDescriptor)
             .map(descriptorModule19.toMemoryLayout)
             .toSeq*
         )
       case _ =>
         JFunctionDescriptor.ofVoid(
           descriptor.inputDescriptors.view
+            .map(_.toForeignTypeDescriptor)
             .map(descriptorModule19.toMemoryLayout)
             .toSeq*
         )
@@ -46,17 +48,18 @@ class Allocator19(
       linker.upcallStub(mh, fd, scope).nn
     )
 
-  override def allocate(descriptor: TypeDescriptor, num: Int): Mem = Mem19(
-    segmentAllocator
-      .allocate(descriptor.size.toLong * num, descriptor.alignment.toLong)
-      .nn
-  )
+  override def allocate(descriptor: ForeignTypeDescriptor, num: Int): Mem =
+    Mem19(
+      segmentAllocator
+        .allocate(descriptor.size.toLong * num, descriptor.alignment.toLong)
+        .nn
+    )
 
   override def base: Object = segmentAllocator
 
   private def build(
       builder: VaList.Builder,
-      typeDescriptor: TypeDescriptor,
+      typeDescriptor: ForeignTypeDescriptor,
       value: Matchable
   ): Unit =
     (typeDescriptor, value) match
@@ -90,8 +93,6 @@ class Allocator19(
               .asInstanceOf[MemorySegment]
           )
         )
-      case (AliasDescriptor(real), v) =>
-        build(builder, real, v)
       case (VaListDescriptor, varArg: VarArgs19) =>
         builder.addVarg(
           ValueLayout.ADDRESS,
@@ -134,7 +135,12 @@ class Allocator19(
           val builder = _b.nn
           vbuilder.vs.foreach: variadic =>
             variadic.use[DescriptorOf](dO ?=>
-              v => build(builder, dO.descriptor, v.asMatchable)
+              v =>
+                build(
+                  builder,
+                  dO.descriptor.toForeignTypeDescriptor,
+                  v.asMatchable
+                )
             )
         ,
         scope
diff --git a/j19/src/fr/hammons/slinc/Slinc19.scala b/j19/src/fr/hammons/slinc/Slinc19.scala
index 49b0b3fb..8aeee770 100644
--- a/j19/src/fr/hammons/slinc/Slinc19.scala
+++ b/j19/src/fr/hammons/slinc/Slinc19.scala
@@ -16,8 +16,6 @@ class Slinc19()(using
 
 @SlincImpl(19)
 object Slinc19:
-  private val compiler =
-    scala.quoted.staging.Compiler.make(getClass().getClassLoader().nn)
   private[slinc] lazy val linker = Linker.nativeLinker().nn
   val default = Slinc19()
   val noJit = Slinc19()
diff --git a/j19/src/fr/hammons/slinc/VarArgs19.scala b/j19/src/fr/hammons/slinc/VarArgs19.scala
index dceb2249..896f5fc1 100644
--- a/j19/src/fr/hammons/slinc/VarArgs19.scala
+++ b/j19/src/fr/hammons/slinc/VarArgs19.scala
@@ -20,7 +20,7 @@ private class VarArgs19(vaList: VaList) extends VarArgs:
     .nn
     .pipe(Mem19.apply(_))
 
-  private def skip(td: TypeDescriptor): Unit = td match
+  private def skip(td: ForeignTypeDescriptor): Unit = td match
     case ByteDescriptor | ShortDescriptor | IntDescriptor =>
       vaList.skip(ValueLayout.JAVA_INT)
     case LongDescriptor => vaList.skip(ValueLayout.JAVA_LONG)
@@ -32,13 +32,14 @@ private class VarArgs19(vaList: VaList) extends VarArgs:
       vaList.skip(descriptorModule19.toGroupLayout(sd))
     case cd: CUnionDescriptor =>
       vaList.skip(descriptorModule19.toMemoryLayout(cd))
-    case AliasDescriptor(real) => skip(real)
 
-  override def skip[A](using dO: DescriptorOf[A]): Unit = skip(dO.descriptor)
+  override def skip[A](using dO: DescriptorOf[A]): Unit = skip(
+    dO.descriptor.toForeignTypeDescriptor
+  )
 
   override def copy(): VarArgs = VarArgs19(vaList.copy().nn)
 
-  def as(td: TypeDescriptor): Object =
+  def as(td: ForeignTypeDescriptor): Object =
     td match
       case ByteDescriptor =>
         Byte.box(vaList.nextVarg(ValueLayout.JAVA_INT).toByte)
@@ -63,11 +64,7 @@ private class VarArgs19(vaList: VaList) extends VarArgs:
             )
             .nn
         )
-      case AliasDescriptor(real) => as(real)
       case cud: CUnionDescriptor =>
-        val desc =
-          descriptorModule19.toMemoryLayout(cud).asInstanceOf[GroupLayout]
-
         LinkageModule19.tempScope(alloc ?=>
           vaList
             .nextVarg(
@@ -77,4 +74,5 @@ private class VarArgs19(vaList: VaList) extends VarArgs:
             .nn
         )
   override def get[A](using d: DescriptorOf[A]): A =
-    transitionModule19.methodReturn[A](d.descriptor, as(d.descriptor))
+    transitionModule19
+      .methodReturn[A](d.descriptor, as(d.descriptor.toForeignTypeDescriptor))
diff --git a/j19/src/fr/hammons/slinc/modules/DescriptorModule19.scala b/j19/src/fr/hammons/slinc/modules/DescriptorModule19.scala
index bc8250d0..63a03b26 100644
--- a/j19/src/fr/hammons/slinc/modules/DescriptorModule19.scala
+++ b/j19/src/fr/hammons/slinc/modules/DescriptorModule19.scala
@@ -13,7 +13,7 @@ given descriptorModule19: DescriptorModule with
   private val sdt = TrieMap.empty[StructDescriptor, GroupLayout]
   private val offsets = TrieMap.empty[List[TypeDescriptor], IArray[Bytes]]
 
-  def toMemoryLayout(td: TypeDescriptor): MemoryLayout = td match
+  def toMemoryLayout(td: ForeignTypeDescriptor): MemoryLayout = td match
     case ByteDescriptor   => ValueLayout.JAVA_BYTE.nn
     case ShortDescriptor  => ValueLayout.JAVA_SHORT.nn
     case IntDescriptor    => ValueLayout.JAVA_INT.nn
@@ -23,14 +23,22 @@ given descriptorModule19: DescriptorModule with
     case PtrDescriptor    => ValueLayout.ADDRESS.nn
     case VaListDescriptor => ValueLayout.ADDRESS.nn
     case SetSizeArrayDescriptor(inner, num) =>
-      MemoryLayout.sequenceLayout(num, toMemoryLayout(inner)).nn
-    case sd: StructDescriptor   => toGroupLayout(sd)
-    case ad: AliasDescriptor[?] => toMemoryLayout(ad.real)
+      MemoryLayout
+        .sequenceLayout(num, toMemoryLayout(inner.toForeignTypeDescriptor))
+        .nn
+    case sd: StructDescriptor => toGroupLayout(sd)
     case CUnionDescriptor(possibleTypes) =>
-      MemoryLayout.unionLayout(possibleTypes.view.map(toMemoryLayout).toSeq*).nn
+      MemoryLayout
+        .unionLayout(
+          possibleTypes.view
+            .map(_.toForeignTypeDescriptor)
+            .map(toMemoryLayout)
+            .toSeq*
+        )
+        .nn
 
   def toMemoryLayout(smd: StructMemberDescriptor): MemoryLayout =
-    toMemoryLayout(smd.descriptor).withName(smd.name).nn
+    toMemoryLayout(smd.descriptor.toForeignTypeDescriptor).withName(smd.name).nn
 
   def toGroupLayout(sd: StructDescriptor): GroupLayout =
     sdt.getOrElseUpdate(
@@ -81,11 +89,11 @@ given descriptorModule19: DescriptorModule with
     )
 
   def toDowncallLayout(td: TypeDescriptor): MemoryLayout =
-    toMemoryLayout(td) match
+    toMemoryLayout(td.toForeignTypeDescriptor) match
       case _: SequenceLayout => ValueLayout.ADDRESS.nn
       case o                 => o
 
-  def toCarrierType(td: TypeDescriptor): Class[?] = td match
+  override def toCarrierType(td: ForeignTypeDescriptor): Class[?] = td match
     case ByteDescriptor   => classOf[Byte]
     case ShortDescriptor  => classOf[Short]
     case IntDescriptor    => classOf[Int]
@@ -96,9 +104,8 @@ given descriptorModule19: DescriptorModule with
       classOf[MemoryAddress]
     case _: StructDescriptor | _: CUnionDescriptor =>
       classOf[MemorySegment]
-    case ad: AliasDescriptor[?] => toCarrierType(ad.real)
 
-  override def memberOffsets(sd: List[TypeDescriptor]): IArray[Bytes] =
+  override def memberOffsets(sd: List[ForeignTypeDescriptor]): IArray[Bytes] =
     offsets.getOrElseUpdate(
       sd, {
         val ll = genLayoutList(
@@ -125,10 +132,10 @@ given descriptorModule19: DescriptorModule with
       }
     )
 
-  override def sizeOf(td: TypeDescriptor): Bytes = Bytes(
+  override def sizeOf(td: ForeignTypeDescriptor): Bytes = Bytes(
     toMemoryLayout(td).byteSize()
   )
 
-  override def alignmentOf(td: TypeDescriptor): Bytes = Bytes(
+  override def alignmentOf(td: ForeignTypeDescriptor): Bytes = Bytes(
     toMemoryLayout(td).byteAlignment()
   )
diff --git a/j19/src/fr/hammons/slinc/modules/LinkageModule19.scala b/j19/src/fr/hammons/slinc/modules/LinkageModule19.scala
index 507c3886..5a6eb099 100644
--- a/j19/src/fr/hammons/slinc/modules/LinkageModule19.scala
+++ b/j19/src/fr/hammons/slinc/modules/LinkageModule19.scala
@@ -50,6 +50,7 @@ object LinkageModule19 extends LinkageModule:
         .map(toDowncallLayout),
       varargs.view
         .map(_.use[DescriptorOf](dc ?=> _ => dc.descriptor))
+        .map(_.toForeignTypeDescriptor)
         .map(toMemoryLayout)
         .toList
     )
diff --git a/j19/src/fr/hammons/slinc/modules/ReadWriteModule19.scala b/j19/src/fr/hammons/slinc/modules/ReadWriteModule19.scala
index 916edb7e..fa803f22 100644
--- a/j19/src/fr/hammons/slinc/modules/ReadWriteModule19.scala
+++ b/j19/src/fr/hammons/slinc/modules/ReadWriteModule19.scala
@@ -11,16 +11,16 @@ private[slinc] given readWriteModule19: ReadWriteModule with
   override def unionWriter(
       td: TypeDescriptor
   ): Writer[CUnion[? <: NonEmptyTuple]] =
-    val size = descriptorModule19.sizeOf(td)
+    val size = descriptorModule19.sizeOf(td.toForeignTypeDescriptor)
     (mem, offset, value) => mem.offset(offset).resize(size).copyFrom(value.mem)
 
   override def unionReader(
       td: TypeDescriptor
   ): Reader[CUnion[? <: NonEmptyTuple]] =
-    val size = descriptorModule19.sizeOf(td)
+    val size = descriptorModule19.sizeOf(td.toForeignTypeDescriptor)
     (mem, offset) =>
       Scope19.createInferredScope(alloc ?=>
-        val newMem = alloc.allocate(td, 1)
+        val newMem = alloc.allocate(td.toForeignTypeDescriptor, 1)
         newMem.copyFrom(mem.offset(offset).resize(size))
         new CUnion(newMem)
       )