diff --git a/test/thread/mutex.cpp b/test/thread/mutex.cpp
index 288a0081..cace788f 100644
--- a/test/thread/mutex.cpp
+++ b/test/thread/mutex.cpp
@@ -7,6 +7,8 @@ int main ()
 
     cruft::thread::mutex a;
     cruft::thread::mutex b;
+    (void)a;
+    (void)b;
 
     return tap.status ();
 }
\ No newline at end of file