diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 6680e4f..dc5f40e 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -5,6 +5,7 @@
 %option stack
 %option bison-locations
 %option yylineno
+%option reject
 
 %{
 #include <errno.h>