diff --git a/lib/multi.c b/lib/multi.c
index 062d09cc0b..78e5c0a1e5 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -3688,6 +3688,8 @@ CURLMcode curl_multi_assign(struct Curl_multi *multi, curl_socket_t s,
                             void *hashp)
 {
   struct Curl_sh_entry *there = NULL;
+  if(!GOOD_MULTI_HANDLE(multi))
+    return CURLM_BAD_HANDLE;
 
   there = sh_getentry(&multi->sockhash, s);