1 files changed, 5 insertions, 1 deletions
diff --git a/Parser/grammar1.c b/Parser/grammar1.c
index 1f7d264be9..440ba44cb0 100644
--- a/Parser/grammar1.c
+++ b/Parser/grammar1.c
@@ -45,7 +45,7 @@ PyGrammar_LabelRepr(label *lb)
         else
             return lb->lb_str;
     }
-    else {
+    else if (lb->lb_type < N_TOKENS) {
         if (lb->lb_str == NULL)
             return _PyParser_TokenNames[lb->lb_type];
         else {
@@ -54,4 +54,8 @@ PyGrammar_LabelRepr(label *lb)
             return buf;
         }
     }
+    else {
+        Py_FatalError("invalid label");
+        return NULL;
+    }
 }