diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 1539960ba23b..f588cce60194 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -865,6 +865,12 @@ static char *pmu_id(const char *name)
 	if (filename__read_str(path, &str, &len) < 0)
 		return NULL;
 
+	/* empty identifier file — nothing useful */
+	if (len == 0) {
+		free(str);
+		return NULL;
+	}
+
 	str[len - 1] = 0; /* remove line feed */
 
 	return str;