diff --git a/.travis.yml b/.travis.yml
index add12ec..73f3c9e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,5 +3,5 @@ compiler:
     - gcc
     - clang
 script:
-    - gcc -O3 test.cpp -o test
+    - $CC -O3 test.cpp -o test
 
diff --git a/test.cpp b/test.cpp
index 519dfec..feec63d 100644
--- a/test.cpp
+++ b/test.cpp
@@ -20,8 +20,9 @@ LatencySimulator *vnet;
 // 模拟网络：模拟发送一个 udp包
 int udp_output(const char *buf, int len, ikcpcb *kcp, void *user)
 {
-	int id = (int)user;
-	vnet->send(id, buf, len);
+	union { int id; void *ptr; } parameter;
+	parameter.ptr = user;
+	vnet->send(parameter.id, buf, len);
 	return 0;
 }