diff --git a/clatd.c b/clatd.c
index 06ca799..d68dc05 100644
--- a/clatd.c
+++ b/clatd.c
@@ -381,7 +381,7 @@
     logmsg(ANDROID_LOG_WARN, "ipv4mtu now set to = %d", Global_Clatd_Config.ipv4mtu);
   }
 
-  error = tun_alloc(tunnel->device4, tunnel->fd4);
+  error = tun_alloc(tunnel->device4, tunnel->fd4, sizeof(tunnel->device4));
   if (error < 0) {
     logmsg(ANDROID_LOG_FATAL, "tun_alloc/4 failed: %s", strerror(errno));
     exit(1);