diff --git a/gen/src/write.rs b/gen/src/write.rs
index 8cc1b1b..a6f6c3e 100644
--- a/gen/src/write.rs
+++ b/gen/src/write.rs
@@ -217,6 +217,7 @@
                     out.include.string = true;
                     needs_rust_str = true;
                     needs_rust_error = true;
+                    needs_maybe_uninit = true;
                 }
                 for arg in &efn.args {
                     if arg.ty != RustString && types.needs_indirect_abi(&arg.ty) {