diff --git a/tools/perf/tests/sdt.c b/tools/perf/tests/sdt.c
index f59d210e1bafbe21f5689587b718a8fb04f252cc..26e5b7a0b839d1b87611201ecf3bf7ede912c5ed 100644
--- a/tools/perf/tests/sdt.c
+++ b/tools/perf/tests/sdt.c
@@ -43,7 +43,7 @@ static char *get_self_path(void)
 {
 	char *buf = calloc(PATH_MAX, sizeof(char));
 
-	if (buf && readlink("/proc/self/exe", buf, PATH_MAX) < 0) {
+	if (buf && readlink("/proc/self/exe", buf, PATH_MAX - 1) < 0) {
 		pr_debug("Failed to get correct path of perf\n");
 		free(buf);
 		return NULL;