diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index fa74631..1b6a453 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -3845,7 +3845,7 @@
     /* Resize if we allocated to much */
     size = str - PyBytes_AS_STRING(res);
     if (size < ressize) { /* If this falls res will be NULL */
-        assert(size > 0);
+        assert(size >= 0);
         if (_PyBytes_Resize(&res, size) < 0)
             goto onError;
     }