diff --git a/parse.y b/parse.y
index c51e9ed1f6..02b75b4410 100644
--- a/parse.y
+++ b/parse.y
@@ -4905,6 +4905,8 @@ cond0(node)
 	else {
 	    rb_warning("literal in condition");
 	}
+      default:
+	break;
     }
     return node;
 }