diff --git a/src/rpcwallet.cpp b/src/rpcwallet.cpp
index cc2e8ab46..6f8728e97 100644
--- a/src/rpcwallet.cpp
+++ b/src/rpcwallet.cpp
@@ -329,12 +329,12 @@ Value signmessage(const Array& params, bool fHelp)
     if (!pwalletMain->GetKey(keyID, key))
         throw JSONRPCError(RPC_WALLET_ERROR, "Private key not available");
 
-    CDataStream ss(SER_GETHASH, 0);
+    CHashWriter ss(SER_GETHASH, 0);
     ss << strMessageMagic;
     ss << strMessage;
 
     vector<unsigned char> vchSig;
-    if (!key.SignCompact(Hash(ss.begin(), ss.end()), vchSig))
+    if (!key.SignCompact(ss.GetHash(), vchSig))
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Sign failed");
 
     return EncodeBase64(&vchSig[0], vchSig.size());
@@ -365,12 +365,12 @@ Value verifymessage(const Array& params, bool fHelp)
     if (fInvalid)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Malformed base64 encoding");
 
-    CDataStream ss(SER_GETHASH, 0);
+    CHashWriter ss(SER_GETHASH, 0);
     ss << strMessageMagic;
     ss << strMessage;
 
     CKey key;
-    if (!key.SetCompactSignature(Hash(ss.begin(), ss.end()), vchSig))
+    if (!key.SetCompactSignature(ss.GetHash(), vchSig))
         return false;
 
     return (key.GetPubKey().GetID() == keyID);
diff --git a/src/script.cpp b/src/script.cpp
index 61112b17c..36d208c24 100644
--- a/src/script.cpp
+++ b/src/script.cpp
@@ -1183,10 +1183,9 @@ uint256 SignatureHash(CScript scriptCode, const CTransaction& txTo, unsigned int
     }
 
     // Serialize and hash
-    CDataStream ss(SER_GETHASH, 0);
-    ss.reserve(10000);
+    CHashWriter ss(SER_GETHASH, 0);
     ss << txTmp << nHashType;
-    return Hash(ss.begin(), ss.end());
+    return ss.GetHash();
 }