diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
index 9d995dd4..902665cc 100644
--- a/src/openvpn/tun.h
+++ b/src/openvpn/tun.h
@@ -130,7 +130,7 @@ struct tuntap_options {
     int dns6_len;
 };
 
-#elif TARGET_LINUX
+#elif defined(TARGET_LINUX)
 
 struct tuntap_options {
     int txqueuelen;