diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c
index 9ad9da0f215e..56ed1eb9b527 100644
--- a/tools/testing/selftests/bpf/prog_tests/usdt.c
+++ b/tools/testing/selftests/bpf/prog_tests/usdt.c
@@ -314,6 +314,7 @@ static FILE *urand_spawn(int *pid)
 
 	if (fscanf(f, "%d", pid) != 1) {
 		pclose(f);
+		errno = EINVAL;
 		return NULL;
 	}