diff --git a/vm/ffi_test.c b/vm/ffi_test.c
index 2bef4a5465..e830b50a30 100644
--- a/vm/ffi_test.c
+++ b/vm/ffi_test.c
@@ -333,3 +333,14 @@ struct ulonglong_pair ffi_test_63() {
   return ullp;
 }
 
+void* bug1021_test_1(void* x, int y) {
+  return (void*)((y * y) + (long)x);
+}
+
+int bug1021_test_2(int x, char *y, void *z) {
+  return y[0];
+}
+
+void* bug1021_test_3(int x) {
+  return (void*)((long)x);
+}
diff --git a/vm/ffi_test.h b/vm/ffi_test.h
index e813ec990d..3c7ff1edba 100644
--- a/vm/ffi_test.h
+++ b/vm/ffi_test.h
@@ -231,3 +231,6 @@ struct ulonglong_pair {
 
 FACTOR_EXPORT struct ulonglong_pair ffi_test_63();
 
+FACTOR_EXPORT void* bug1021_test_1(void* x, int y);
+FACTOR_EXPORT int bug1021_test_2(int x, char* y, void *z);
+FACTOR_EXPORT void* bug1021_test_3(int x);