diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index 702ba3a8ead6f425bdca21489e76ce187d163f24..37a08f20730af9b5eb6af41e84a5525b050030a6 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -417,6 +417,8 @@ static int hist_entry__init(struct hist_entry *he,
 	}
 	INIT_LIST_HEAD(&he->pairs.node);
 	thread__get(he->thread);
+	he->hroot_in  = RB_ROOT;
+	he->hroot_out = RB_ROOT;
 
 	if (!symbol_conf.report_hierarchy)
 		he->leaf = true;