diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -10582,7 +10582,7 @@
     if (kind == PyUnicode_1BYTE_KIND) {
         char *data = PyUnicode_1BYTE_DATA(uni);
         Py_ssize_t len1 = PyUnicode_GET_LENGTH(uni);
-        size_t len, len2 = strlen(str);
+        Py_ssize_t len, len2 = strlen(str);
         int cmp;
 
         len = Py_MIN(len1, len2);