diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index e5d026f..04ca5f3 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -6069,7 +6069,7 @@
             }
 
             message = "malformed \\N character escape";
-            if (*s == '{') {
+            if (s < end && *s == '{') {
                 const char *start = ++s;
                 size_t namelen;
                 /* look for the closing brace */