diff --git a/tools/perf/bench/inject-buildid.c b/tools/perf/bench/inject-buildid.c
index 49331743c7439..a759eb2328bea 100644
--- a/tools/perf/bench/inject-buildid.c
+++ b/tools/perf/bench/inject-buildid.c
@@ -362,7 +362,7 @@ static int inject_build_id(struct bench_data *data, u64 *max_rss)
 		return -1;
 
 	for (i = 0; i < nr_mmaps; i++) {
-		int idx = rand() % (nr_dsos - 1);
+		int idx = rand() % nr_dsos;
 		struct bench_dso *dso = &dsos[idx];
 		u64 timestamp = rand() % 1000000;