diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index e54c8e042a5..79d292f1ae4 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -628,6 +628,8 @@ PyInit_fcntl(void)
         return NULL;
 
     /* Add some symbolic constants to the module */
-    all_ins(m);
+    if (all_ins(m) < 0)
+        return NULL;
+
     return m;
 }