diff --git a/app/lib/kredits/kredits.js b/app/lib/kredits/kredits.js
index 46a893f..1463621 100644
--- a/app/lib/kredits/kredits.js
+++ b/app/lib/kredits/kredits.js
@@ -94,7 +94,8 @@ export default class Kredits {
     if (!address || !abis[contractName]) {
       throw new Error(`Address or ABI not found for ${contractName}`);
     }
-    let contract = new ethers.Contract(address, abis[contractName], this.signer);
+    let signerOrProvider = this.signer || this.provider;
+    let contract = new ethers.Contract(address, abis[contractName], signerOrProvider);
     this.contracts[name] = new contracts[contractName](contract);
 
     return this.contracts[name];
diff --git a/app/services/kredits.js b/app/services/kredits.js
index 464dce1..d6e11a1 100644
--- a/app/services/kredits.js
+++ b/app/services/kredits.js
@@ -31,37 +31,40 @@ export default Service.extend({
   initEthProvider: function() {
     return new RSVP.Promise((resolve) => {
       let ethProvider;
+      let ethSigner;
       let networkId;
       if (typeof window.web3 !== 'undefined') {
         console.debug('[kredits] Using user-provided instance, e.g. from Mist browser or Metamask');
         networkId = parseInt(window.web3.version.network);
         ethProvider = new ethers.providers.Web3Provider(window.web3.currentProvider, {chainId: networkId});
+        ethSigner = ethProvider.getSigner();
         ethProvider.listAccounts().then((accounts) => {
           this.set('currentUserAccounts', accounts);
           this.set('ethProvider', ethProvider);
-          resolve(ethProvider);
+          this.set('ethSigner', ethSigner);
+          resolve(ethProvider, ethSigner);
         });
       } else {
         console.debug('[kredits] Creating new instance from npm module class');
         let providerUrl = localStorage.getItem('config:web3ProviderUrl') || config.web3ProviderUrl;
         networkId = parseInt(config.contractMetadata.networkId);
         ethProvider = new ethers.providers.JsonRpcProvider(providerUrl, {chainId: networkId});
+        ethSigner = null; // no signer as no local web3 object is available
         this.set('ethProvider', ethProvider);
-        resolve(ethProvider);
+        this.set('ethSigner', ethSigner);
+        resolve(ethProvider, ethSigner);
       }
       window.ethProvider = ethProvider;
     });
   },
 
   setup() {
-    return this.initEthProvider().then((ethProvider) => {
-      let signer = ethProvider.getSigner();
-      return Kredits.setup(ethProvider, signer, config.ipfs).then((kredits) => {
+    return this.initEthProvider().then((ethProvider, ethSigner) => {
+      return Kredits.setup(ethProvider, ethSigner, config.ipfs).then((kredits) => {
           this.set('kredits', kredits);
-
-          // TODO: Cleanup
-          if (this.currentUserAccounts.length > 0) {
-            this.getCurrentUser.then((contributorData) => {
+          // TODO: Cleanup (!!!)
+          if (this.currentUserAccounts && this.currentUserAccounts.length > 0) {
+            this.getCurrentUser.then(contributorData => {
               this.set('currentUser', contributorData);
             });
           }
diff --git a/app/utils/cps/bignumber.js b/app/utils/cps/bignumber.js
index 2bf5bf7..d194685 100644
--- a/app/utils/cps/bignumber.js
+++ b/app/utils/cps/bignumber.js
@@ -4,7 +4,12 @@ import ethers from 'npm:ethers';
 export default function(dependentKey, converterMethod) {
   return computed(dependentKey, {
     get () {
-      return this.get(dependentKey)[converterMethod]();
+      let value = this.get(dependentKey);
+      if (value && ethers.utils.isBigNumber(value)) {
+        return value[converterMethod]();
+      } else {
+        return value;
+      }
     },
     set (key, value) {
       value = ethers.utils.bigNumberify(value);