diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 0eab0626e..9dfd640df 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -144,9 +144,9 @@ static CScript PushAll(const vector<valtype>& values)
     return result;
 }
 
-static CScript CombineMultisig(CScript scriptPubKey, const CMutableTransaction& txTo, unsigned int nIn,
+static CScript CombineMultisig(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn,
                                const vector<valtype>& vSolutions,
-                               vector<valtype>& sigs1, vector<valtype>& sigs2)
+                               const vector<valtype>& sigs1, const vector<valtype>& sigs2)
 {
     // Combine all the signatures we've got:
     set<valtype> allsigs;
@@ -199,7 +199,7 @@ static CScript CombineMultisig(CScript scriptPubKey, const CMutableTransaction&
     return result;
 }
 
-static CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo, unsigned int nIn,
+static CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn,
                                  const txnouttype txType, const vector<valtype>& vSolutions,
                                  vector<valtype>& sigs1, vector<valtype>& sigs2)
 {
@@ -244,7 +244,7 @@ static CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo,
     return CScript();
 }
 
-CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo, unsigned int nIn,
+CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn,
                           const CScript& scriptSig1, const CScript& scriptSig2)
 {
     txnouttype txType;
diff --git a/src/script/sign.h b/src/script/sign.h
index c84d3f9a9..99d5516ad 100644
--- a/src/script/sign.h
+++ b/src/script/sign.h
@@ -19,6 +19,6 @@ bool SignSignature(const CKeyStore& keystore, const CTransaction& txFrom, CMutab
 
 // Given two sets of signatures for scriptPubKey, possibly with OP_0 placeholders,
 // combine them intelligently and return the result.
-CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CScript& scriptSig1, const CScript& scriptSig2);
+CScript CombineSignatures(const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn, const CScript& scriptSig1, const CScript& scriptSig2);
 
 #endif // BITCOIN_SCRIPT_SIGN_H