diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 75a32ae8ef62..3583a60cc487 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1221,8 +1221,8 @@ int perf_event__synthesize_threads(const struct perf_tool *tool,
 	}
 	err = 0;
 out_join:
-	for (i = 0; i < thread_nr; i++)
-		pthread_join(synthesize_threads[i], NULL);
+	for (j = 0; j < i; j++)
+		pthread_join(synthesize_threads[j], NULL);
 	free(args);
 free_threads:
 	free(synthesize_threads);