diff --git a/win32/wintap.c b/win32/wintap.c
index e228ca1..66fb08d 100644
--- a/win32/wintap.c
+++ b/win32/wintap.c
@@ -277,7 +277,7 @@ int open_wintap(struct tuntap_dev *device,
 
   /* ************************************** */
 
-  if(device_mac[0])
+  if(device_mac && device_mac[0])
     set_interface_mac(device, device_mac);
 
     /* Get MAC address from tap device->device_name */