diff --git a/src/script/interpreter.h b/src/script/interpreter.h
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -29,6 +29,10 @@
 
 class BaseSignatureChecker {
 public:
+    virtual bool VerifySignature(const std::vector<uint8_t> &vchSig,
+                                 const CPubKey &vchPubKey,
+                                 const uint256 &sighash) const;
+
     virtual bool CheckSig(const std::vector<uint8_t> &scriptSig,
                           const std::vector<uint8_t> &vchPubKey,
                           const CScript &scriptCode, uint32_t flags) const {
@@ -53,11 +57,6 @@
     const Amount amount;
     const PrecomputedTransactionData *txdata;
 
-protected:
-    virtual bool VerifySignature(const std::vector<uint8_t> &vchSig,
-                                 const CPubKey &vchPubKey,
-                                 const uint256 &sighash) const;
-
 public:
     TransactionSignatureChecker(const CTransaction *txToIn, unsigned int nInIn,
                                 const Amount amountIn)
@@ -66,11 +65,14 @@
                                 const Amount amountIn,
                                 const PrecomputedTransactionData &txdataIn)
         : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}
+
+    // The overriden functions are now final.
     bool CheckSig(const std::vector<uint8_t> &scriptSig,
                   const std::vector<uint8_t> &vchPubKey,
-                  const CScript &scriptCode, uint32_t flags) const override;
-    bool CheckLockTime(const CScriptNum &nLockTime) const override;
-    bool CheckSequence(const CScriptNum &nSequence) const override;
+                  const CScript &scriptCode,
+                  uint32_t flags) const final override;
+    bool CheckLockTime(const CScriptNum &nLockTime) const final override;
+    bool CheckSequence(const CScriptNum &nSequence) const final override;
 };
 
 class MutableTransactionSignatureChecker : public TransactionSignatureChecker {
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -941,9 +941,8 @@
                             CSHA256()
                                 .Write(vchMessage.data(), vchMessage.size())
                                 .Finalize(vchHash.data());
-                            uint256 message(vchHash);
-                            CPubKey pubkey(vchPubKey);
-                            fSuccess = pubkey.Verify(message, vchSig);
+                            fSuccess = checker.VerifySignature(
+                                vchSig, CPubKey(vchPubKey), uint256(vchHash));
                         }
 
                         if (!fSuccess && (flags & SCRIPT_VERIFY_NULLFAIL) &&
@@ -1463,9 +1462,9 @@
     return ss.GetHash();
 }
 
-bool TransactionSignatureChecker::VerifySignature(
-    const std::vector<uint8_t> &vchSig, const CPubKey &pubkey,
-    const uint256 &sighash) const {
+bool BaseSignatureChecker::VerifySignature(const std::vector<uint8_t> &vchSig,
+                                           const CPubKey &pubkey,
+                                           const uint256 &sighash) const {
     return pubkey.Verify(sighash, vchSig);
 }