diff --git a/libgo/runtime/go-map-delete.c b/libgo/runtime/go-map-delete.c
index de8b0469deaf..aff25d104bf4 100644
--- a/libgo/runtime/go-map-delete.c
+++ b/libgo/runtime/go-map-delete.c
@@ -35,7 +35,10 @@ __go_map_delete (struct __go_map *map, const void *key)
   key_descriptor = descriptor->__map_descriptor->__key_type;
   key_offset = descriptor->__key_offset;
   key_size = key_descriptor->__size;
-  __go_assert (key_size != 0 && key_size != -1UL);
+  if (key_size == 0)
+    return;
+
+  __go_assert (key_size != -1UL);
   equalfn = key_descriptor->__equalfn;
 
   key_hash = key_descriptor->__hashfn (key, key_size);