diff --git a/glcpp/glcpp-parse.y b/glcpp/glcpp-parse.y
index f9fab8bf293..fde9b92edec 100644
--- a/glcpp/glcpp-parse.y
+++ b/glcpp/glcpp-parse.y
@@ -360,7 +360,9 @@ text_line:
 ;
 
 non_directive:
-	pp_tokens NEWLINE
+	pp_tokens NEWLINE {
+		yyerror (parser, "Invalid tokens after #");
+	}
 ;
 
 replacement_list: