diff --git a/src/config.js b/src/config.js
index 27aabae8..c50b7cf6 100644
--- a/src/config.js
+++ b/src/config.js
@@ -14,7 +14,7 @@ module.exports.WG_HOST = process.env.WG_HOST;
 module.exports.WG_PORT = process.env.WG_PORT || '51820';
 module.exports.WG_MTU = process.env.WG_MTU || null;
 module.exports.WG_PERSISTENT_KEEPALIVE = process.env.WG_PERSISTENT_KEEPALIVE || '0';
-module.exports.WG_DEFAULT_ADDRESS = process.env.WG_DEFAULT_ADDRESS.replace('x', '0') || '10.8.0.0';
+module.exports.WG_DEFAULT_ADDRESS = (process.env.WG_DEFAULT_ADDRESS && process.env.WG_DEFAULT_ADDRESS.replace('x', '0')) || '10.8.0.0';
 module.exports.WG_DEFAULT_ADDRESS_RANGE = process.env.WG_DEFAULT_ADDRESS_RANGE || '24';
 module.exports.WG_DEFAULT_DNS = typeof process.env.WG_DEFAULT_DNS === 'string'
   ? process.env.WG_DEFAULT_DNS