diff --git a/.github/julia/build_tarballs.jl b/.github/julia/build_tarballs.jl
index d9dc1c82d0..368a5027ac 100644
--- a/.github/julia/build_tarballs.jl
+++ b/.github/julia/build_tarballs.jl
@@ -42,16 +42,35 @@ else
   HWLOC="hwloc"
 fi
 
-meson setup builddir --cross-file=${MESON_TARGET_TOOLCHAIN%.*}_gcc.meson \
-                     --prefix=$prefix \
-                     -Dlibhwloc=$HWLOC \
-                     -Dlibblas=openblas \
-                     -Dliblapack=openblas \
-                     -Dquadruple=true \
-                     -Dlibhsl_modules=$prefix/modules
+meson setup builddir_int32 --cross-file=${MESON_TARGET_TOOLCHAIN%.*}_gcc.meson \
+                           --prefix=$prefix \
+                           -Dlibhwloc=$HWLOC \
+                           -Dlibblas=openblas \
+                           -Dliblapack=openblas \
+                           -Dsingle=true \
+                           -Ddouble=true \
+                           -Dquadruple=true \
+                           -Dint64=false \
+                           -Dlibhsl_modules=$prefix/modules
 
-meson compile -C builddir
-meson install -C builddir
+meson compile -C builddir_int32
+meson install -C builddir_int32
+
+meson setup builddir_int64 --cross-file=${MESON_TARGET_TOOLCHAIN%.*}_gcc.meson \
+                           --prefix=$prefix \
+                           -Dlibhwloc=$HWLOC \
+                           -Dlibblas=openblas64_ \
+                           -Dliblapack=openblas64_ \
+                           -Dlibsmumps= \
+                           -Dlibdmumps= \
+                           -Dsingle=true \
+                           -Ddouble=true \
+                           -Dquadruple=true \
+                           -Dint64=true \
+                           -Dlibhsl_modules=$prefix/modules
+
+meson compile -C builddir_int64
+meson install -C builddir_int64
 """
 
 # These are the platforms we will build for by default, unless further
@@ -63,7 +82,10 @@ platforms = expand_gfortran_versions(platforms)
 products = [
     LibraryProduct("libgalahad_single", :libgalahad_single),
     LibraryProduct("libgalahad_double", :libgalahad_double),
-    LibraryProduct("libgalahad_quadruple", :libgalahad_quadruple)
+    LibraryProduct("libgalahad_quadruple", :libgalahad_quadruple),
+    LibraryProduct("libgalahad_single_64", :libgalahad_single_64),
+    LibraryProduct("libgalahad_double_64", :libgalahad_double_64),
+    LibraryProduct("libgalahad_quadruple_64", :libgalahad_quadruple_64),
 ]
 
 # Dependencies that must be installed before this package can be built
@@ -73,7 +95,7 @@ dependencies = [
     Dependency(PackageSpec(name="OpenBLAS32_jll", uuid="656ef2d0-ae68-5445-9ca0-591084a874a2")),
     Dependency(PackageSpec(name="Hwloc_jll", uuid="e33a78d0-f292-5ffc-b300-72abe9b543c8")),
     Dependency(PackageSpec(name="MUMPS_seq_jll", uuid="d7ed1dd3-d0ae-5e8e-bfb4-87a502085b8d"), compat="=5.4.1"),
-    Dependency(PackageSpec(name="HSL_jll", uuid="017b0a0e-03f4-516a-9b91-836bbd1904dd")),
+    # Dependency(PackageSpec(name="HSL_jll", uuid="017b0a0e-03f4-516a-9b91-836bbd1904dd")),
 ]
 
 # Build the tarballs, and possibly a `build.jl` as well.