diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index ad0e2e3..d5d83fd 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -1254,10 +1254,10 @@
             for (i=0; i < how_many; i++) {
                 ch = PyUnicode_READ(from_kind, from_data, from_start + i);
 #ifndef Py_DEBUG
-                assert(ch <= to_maxchar);
-#else
                 if (ch > to_maxchar)
                     return -1;
+#else
+                assert(ch <= to_maxchar);
 #endif
                 PyUnicode_WRITE(to_kind, to_data, to_start + i, ch);
             }