diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 899080a..f06b0a4 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -845,7 +845,8 @@
 		die("Unknown type of information\n");
 }
 
-static int process_sample_event(union perf_event *event,
+static int process_sample_event(struct perf_event_ops *ops __used,
+				union perf_event *event,
 				struct perf_sample *sample,
 				struct perf_evsel *evsel __used,
 				struct perf_session *s)