diff --git a/random.c b/random.c
index f786cacc13..e5676656cc 100644
--- a/random.c
+++ b/random.c
@@ -402,6 +402,8 @@ fill_random_bytes_syscall(void *seed, size_t size, int unused)
 	old_prov = (HCRYPTPROV)ATOMIC_PTR_CAS(perm_prov, 0, prov);
 	if (LIKELY(!old_prov)) { /* no other threads acquired */
 	    if (prov != (HCRYPTPROV)INVALID_HANDLE_VALUE) {
+#undef RUBY_UNTYPED_DATA_WARNING
+#define RUBY_UNTYPED_DATA_WARNING 0
 		rb_gc_register_mark_object(Data_Wrap_Struct(0, 0, release_crypt, &perm_prov));
 	    }
 	}