diff --git a/src/gallium/auxiliary/os/os_thread.h b/src/gallium/auxiliary/os/os_thread.h
index d9c685922a5..f2629c5ffe5 100644
--- a/src/gallium/auxiliary/os/os_thread.h
+++ b/src/gallium/auxiliary/os/os_thread.h
@@ -56,6 +56,8 @@ __pipe_mutex_assert_locked(mtx_t *mutex)
    assert(ret == thrd_busy);
    if (ret == thrd_success)
       mtx_unlock(mutex);
+#else
+   (void)mutex;
 #endif
 }