diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 0de7258..eed1cb8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -70,6 +70,7 @@
 
 	memcpy(self->filename, filename, len);
 	self->threads = RB_ROOT;
+	self->stats_by_id = RB_ROOT;
 	self->last_match = NULL;
 	self->mmap_window = 32;
 	self->cwd = NULL;