diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 4a64739c67e7..c87cfe6b7c96 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3583,7 +3583,7 @@ perf_event__synthesize_event_update_unit(struct perf_tool *tool,
 	if (ev == NULL)
 		return -ENOMEM;
 
-	strncpy(ev->data, evsel->unit, size);
+	strlcpy(ev->data, evsel->unit, size + 1);
 	err = process(tool, (union perf_event *)ev, NULL, NULL);
 	free(ev);
 	return err;