diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 99dc58e5dcc3f2b015f02d7e2c3a7fbbdf3b2da0..3960560f873a4078e29a9b4e34b2379ffca4caab 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -719,6 +719,9 @@ int perf_evlist__parse_mmap_pages(const struct option *opt, const char *str,
 		{ .tag  = 0 },
 	};
 
+	if (str == NULL)
+		return -1;
+
 	val = parse_tag_value(str, tags);
 	if (val != (unsigned long) -1) {
 		/* we got file size value */