diff --git a/.changeset/neat-melons-fix.md b/.changeset/neat-melons-fix.md
new file mode 100644
index 0000000..daee9cc
--- /dev/null
+++ b/.changeset/neat-melons-fix.md
@@ -0,0 +1,5 @@
+---
+"any-ts": patch
+---
+
+fix: re-exports `some.instanceOf`; feat: adds `any.maybeIndexedBy`
diff --git a/src/any/any.ts b/src/any/any.ts
index 9265a04..13ba0bd 100644
--- a/src/any/any.ts
+++ b/src/any/any.ts
@@ -205,6 +205,13 @@ declare namespace any {
     = { [ix in invariant]: _ }
   > = type
 
+  export type maybeIndexedBy<
+    invariant extends any.index,
+    type extends
+    | { [ix in invariant]+?: _ }
+    = { [ix in invariant]+?: _ }
+  > = type
+
   export type indexableBy<
     invariant extends any.index,
     type extends
diff --git a/src/some/some.ts b/src/some/some.ts
index 87ba67f..ed4a2fc 100644
--- a/src/some/some.ts
+++ b/src/some/some.ts
@@ -65,6 +65,8 @@ export declare namespace some {
     some_fieldOf as fieldOf,
     /** {@link some_subtypeOf `some.subtypeOf`} @external */
     some_subtypeOf as subtypeOf,
+    /** {@link some_instanceOf `some.instanceOf`} @external */
+    some_instanceOf as instanceOf,
   }
 }