diff --git a/gc.c b/gc.c
index d5919d19dc..1bc1ce9fd1 100644
--- a/gc.c
+++ b/gc.c
@@ -2734,7 +2734,7 @@ static inline void
 make_io_zombie(rb_objspace_t *objspace, VALUE obj)
 {
     rb_io_t *fptr = RANY(obj)->as.file.fptr;
-    make_zombie(objspace, obj, (void (*)(void*))rb_io_fptr_finalize, fptr);
+    make_zombie(objspace, obj, rb_io_fptr_finalize_internal, fptr);
 }
 
 static void