prevent assignment to set literals
diff --git a/Python/ast.c b/Python/ast.c
index 41c0d28..f8c83d9 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -440,6 +440,7 @@
             expr_name = "dict comprehension";
             break;
         case Dict_kind:
+        case Set_kind:
         case Num_kind:
         case Str_kind:
             expr_name = "literal";