diff --git a/nac3core/src/codegen/model/ptr.rs b/nac3core/src/codegen/model/ptr.rs
index 0684892c..d0b2eeba 100644
--- a/nac3core/src/codegen/model/ptr.rs
+++ b/nac3core/src/codegen/model/ptr.rs
@@ -175,8 +175,16 @@ impl<'ctx, Item: Model<'ctx>> Instance<'ctx, Ptr<Item>> {
         source: Self,
         num_items: IntValue<'ctx>,
     ) {
+        let llvm_usize = generator.get_size_type(ctx.ctx);
+
+        // Force extend `num_items` and `itemsize` so their types would match.
         let itemsize = self.model.sizeof(generator, ctx.ctx);
-        let totalsize = ctx.builder.build_int_mul(itemsize, num_items, "totalsize").unwrap(); // TODO: Int types may not match.
+        let itemsize =
+            ctx.builder.build_int_z_extend_or_bit_cast(itemsize, llvm_usize, "").unwrap();
+        let num_items =
+            ctx.builder.build_int_z_extend_or_bit_cast(num_items, llvm_usize, "").unwrap();
+
+        let totalsize = ctx.builder.build_int_mul(itemsize, num_items, "totalsize").unwrap();
 
         let is_volatile = ctx.ctx.bool_type().const_zero(); // is_volatile = false
         call_memcpy_generic(ctx, self.value, source.value, totalsize, is_volatile);