diff --git a/cmd/cmd_controller.js b/cmd/cmd_controller.js
index 02beae5d2..ae1f46d20 100644
--- a/cmd/cmd_controller.js
+++ b/cmd/cmd_controller.js
@@ -291,9 +291,7 @@ class EmbarkController {
         engine.startService("namingSystem");
         engine.startService("console");
         engine.startService("pluginCommand");
-        engine.events.on('check:backOnline:Ethereum', function () {
-          callback();
-        });
+        engine.events.on('check:backOnline:Ethereum', () => callback());
       },
       function ipcConnect(callback) {
         // Do specific work in case we are connected to a socket:
diff --git a/lib/modules/ens/index.js b/lib/modules/ens/index.js
index 3931e7817..e01f2f9cb 100644
--- a/lib/modules/ens/index.js
+++ b/lib/modules/ens/index.js
@@ -29,8 +29,12 @@ const DEFAULT_ENS_CONTRACTS_CONFIG = {
   }
 };
 
+const MAINNET_ID = '1';
+const ROPSTEN_ID = '3';
+const RINKEBY_ID = '4';
+
 const ENS_CONTRACTS_CONFIG = {
-  "1": {
+  [MAINNET_ID]: {
     "contracts": {
       "ENSRegistry": {
         "address": "0x314159265dd8dbb310642f98f50c066173c1259b",
@@ -44,7 +48,7 @@ const ENS_CONTRACTS_CONFIG = {
       }
     }
   },
-  "3": {
+  [ROPSTEN_ID]: {
     "contracts": {
       "ENSRegistry": {
         "address": "0x112234455c3a32fd11230c42e7bccd4a84e02010",
@@ -58,7 +62,7 @@ const ENS_CONTRACTS_CONFIG = {
       }
     }
   },
-  "4": {
+  [RINKEBY_ID]: {
     "contracts": {
       "ENSRegistry": {
         "address": "0xe7410170f87102DF0055eB195163A03B7F2Bff4A",
@@ -143,9 +147,9 @@ class ENS {
       }
 
       self.events.request('blockchain:networkId', (networkId) => {
-        const isKnownNetworks = Object.keys(ENS_CONTRACTS_CONFIG).includes(networkId);
+        const isKnownNetwork = Object.keys(ENS_CONTRACTS_CONFIG).includes(networkId);
         const shouldRegisterSubdomain = self.registration && self.registration.subdomains && Object.keys(self.registration.subdomains).length;
-        if (isKnownNetworks || !shouldRegisterSubdomain) {
+        if (isKnownNetwork || !shouldRegisterSubdomain) {
           return cb();
         }
         self.registerConfigDomains(config, cb);