diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
index a9dd1b9..46a0d35 100644
--- a/tools/perf/util/hist.c
+++ b/tools/perf/util/hist.c
@@ -24,7 +24,8 @@
 struct callchain_param	callchain_param = {
 	.mode	= CHAIN_GRAPH_REL,
 	.min_percent = 0.5,
-	.order  = ORDER_CALLEE
+	.order  = ORDER_CALLEE,
+	.key	= CCKEY_FUNCTION
 };
 
 u16 hists__col_len(struct hists *hists, enum hist_column col)