diff --git a/src/miner.cpp b/src/miner.cpp
index 0cfb055e..e9a2375a 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -676,6 +676,8 @@ void GenerateGcoins(bool fGenerate, CWallet* pwallet, int nThreads)
         minerThreads = NULL;
     }
 
+    SoftSetBoolArg("-gen", fGenerate);
+
     if (nThreads == 0 || !fGenerate)
         return;
 
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 31147011..0cabd51e 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -152,13 +152,16 @@ Value assignfixedaddress(const Array& params, bool fHelp)
             "\nArguments:\n"
             "1. \"address\"     (string, required) The address to be assigned as the default address.\n"
             "\nResult:\n"
-            "\"address\"    (string) The default gcoin address\n"
+            "{\n"
+            "  \"address\" : true      (boolean) If the default gcoin address is mining\n"
+            "}\n"
             "\nExamples:\n"
             + HelpExampleCli("assignfixedaddress", "")
             + HelpExampleCli("assignfixedaddress", "address")
             + HelpExampleRpc("assignfixedaddress", "address")
         );
 
+    Object result;
     std::string str = params[0].get_str();
     CPubKey newDefaultKey;
     CKeyID keyID;
@@ -169,6 +172,9 @@ Value assignfixedaddress(const Array& params, bool fHelp)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid Gcoin address or key");
     }
 
+    if (keyID == pwalletMain->vchDefaultKey.GetID())
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Same default address");
+
     if (!pwalletMain->GetKeyFromPool(newDefaultKey, address)) {
         if (!pwalletMain->GetPubKey(keyID, newDefaultKey)) {
             throw JSONRPCError(RPC_WALLET_ERROR, "Public key for address " + str + " is not known");
@@ -184,15 +190,12 @@ Value assignfixedaddress(const Array& params, bool fHelp)
             throw JSONRPCError(RPC_WALLET_ERROR, "Cannot write default address");
     }
 
-    if (mapArgs["-gen"] == "1") {
-        GenerateGcoins(true, pwalletMain, atoi(mapArgs["-genproclimit"]));
-        if (mapArgs["-gen"] == "1")
-            str += " mining continues";
-        else
-            str += " mining stops";
-    }
+    if (GetBoolArg("-gen", false))
+        GenerateGcoins(true, pwalletMain, GetArg("-genproclimit", 1));
 
-    return str;
+    result.push_back(Pair(str, GetBoolArg("-gen", false)));
+
+    return result;
 }
 
 // Get a specific amount of new address.
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 4d65b988..c82b1f3d 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2620,7 +2620,7 @@ void CWallet::ViewKeyPool(std::vector<CPubKey>& keys)
     }
 }
 
-int64_t CWallet::SearchKeyPool(const CBitcoinAddress& address) const
+bool CWallet::SearchKeyPool(int64_t& nIndex, const CBitcoinAddress& address) const
 {
     LOCK(cs_wallet);
     CWalletDB walletdb(strWalletFile);
@@ -2629,10 +2629,12 @@ int64_t CWallet::SearchKeyPool(const CBitcoinAddress& address) const
         CKeyPool keypool;
         if (!walletdb.ReadPool(*it, keypool))
             throw runtime_error(_(__func__) + "() : read failed");
-        if (address == CBitcoinAddress(keypool.vchPubKey.GetID()))
-            return (*it);
+        if (address == CBitcoinAddress(keypool.vchPubKey.GetID())) {
+            nIndex = *it;
+            return true;
+        }
     }
-    return -1;
+    return false;
 }
 
 void CWallet::ReserveKeyFromKeyPool(int64_t& nIndex, CKeyPool& keypool)
@@ -2666,12 +2668,13 @@ void CWallet::ReserveKeyFromKeyPool(int64_t& nIndex, CKeyPool& keypool, const CB
     {
         LOCK(cs_wallet);
 
-        // Get the oldest key
+        // Return if the key pool is empty
         if (setKeyPool.empty())
             return;
 
         CWalletDB walletdb(strWalletFile);
-        nIndex = SearchKeyPool(address);
+        if (!SearchKeyPool(nIndex, address))
+            return;
         setKeyPool.erase(nIndex);
         if (!walletdb.ReadPool(nIndex, keypool))
             throw runtime_error(_(__func__) + "() : read failed");
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index e58396bd..d8f707d8 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -682,7 +682,7 @@ class CWallet : public CHDKeyStore, public CValidationInterface
     bool AddKeyPool(CPubKey& key);
     bool EraseKeyPool();
     void ViewKeyPool(std::vector<CPubKey>& keys);
-    int64_t SearchKeyPool(const CBitcoinAddress& address) const;
+    bool SearchKeyPool(int64_t& nIndex, const CBitcoinAddress& address) const;
     void ReserveKeyFromKeyPool(int64_t& nIndex, CKeyPool& keypool);
     void ReserveKeyFromKeyPool(int64_t& nIndex, CKeyPool& keypool, const CBitcoinAddress& address);
     void KeepKey(int64_t nIndex);