diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 3a95a02..6dd4bda 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -54,7 +54,7 @@
 		return -1;
 	}
 
-	session->hists.stats.total += data.period;
+	session->hists.stats.total_period += data.period;
 	return 0;
 }