diff --git a/client_test.go b/client_test.go
index 43163a1f..63a90afd 100644
--- a/client_test.go
+++ b/client_test.go
@@ -539,8 +539,9 @@ func TestConcurrentExchanges(t *testing.T) {
 		block := make(chan struct{})
 		waiting := make(chan struct{})
 
+		mm := m // redeclare m so as not to trip the race detector
 		handler := func(w ResponseWriter, req *Msg) {
-			r := m.Copy()
+			r := mm.Copy()
 			r.SetReply(req)
 
 			waiting <- struct{}{}