diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 6b7d911..e821999 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -32,6 +32,7 @@
 
 static int diff__process_sample_event(union perf_event *event,
 				      struct perf_sample *sample,
+				      struct perf_evsel *evsel __used,
 				      struct perf_session *session)
 {
 	struct addr_location al;