diff --git a/src/pubkey.h b/src/pubkey.h
--- a/src/pubkey.h
+++ b/src/pubkey.h
@@ -10,6 +10,8 @@
 #include "serialize.h"
 #include "uint256.h"
 
+#include <boost/range/adaptor/sliced.hpp>
+
 #include <stdexcept>
 #include <vector>
 
@@ -140,7 +142,11 @@
     /**
      * Check whether a signature is normalized (lower-S).
      */
-    static bool CheckLowS(const std::vector<uint8_t> &vchSig);
+    static bool
+    CheckLowS(const boost::sliced_range<const std::vector<uint8_t>> &vchSig);
+    static bool CheckLowS(const std::vector<uint8_t> &vchSig) {
+        return CheckLowS(vchSig | boost::adaptors::sliced(0, vchSig.size()));
+    }
 
     //! Recover a public key from a compact signature.
     bool RecoverCompact(const uint256 &hash,
diff --git a/src/pubkey.cpp b/src/pubkey.cpp
--- a/src/pubkey.cpp
+++ b/src/pubkey.cpp
@@ -291,7 +291,8 @@
     return pubkey.Derive(out.pubkey, out.chaincode, _nChild, chaincode);
 }
 
-/* static */ bool CPubKey::CheckLowS(const std::vector<uint8_t> &vchSig) {
+bool CPubKey::CheckLowS(
+    const boost::sliced_range<const std::vector<uint8_t>> &vchSig) {
     secp256k1_ecdsa_signature sig;
     if (!ecdsa_signature_parse_der_lax(secp256k1_context_verify, &sig,
                                        &vchSig[0], vchSig.size())) {
diff --git a/src/script/sigencoding.cpp b/src/script/sigencoding.cpp
--- a/src/script/sigencoding.cpp
+++ b/src/script/sigencoding.cpp
@@ -9,6 +9,8 @@
 #include "pubkey.h"
 #include "script_flags.h"
 
+#include <boost/range/adaptor/sliced.hpp>
+
 /**
  * A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len
  * S> <S> <hashtype>, where R and S are not negative (their first byte has its
@@ -90,15 +92,12 @@
 }
 
 static bool IsLowDERSignature(const valtype &vchSig, ScriptError *serror) {
-    if (!IsValidSignatureEncoding(vchSig)) {
-        return set_error(serror, SCRIPT_ERR_SIG_DER);
-    }
-    std::vector<uint8_t> vchSigCopy(vchSig.begin(),
-                                    vchSig.begin() + vchSig.size() - 1);
-    if (!CPubKey::CheckLowS(vchSigCopy)) {
-        return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
+    assert(vchSig.size() > 0);
+    if (CPubKey::CheckLowS(vchSig |
+                           boost::adaptors::sliced(0, vchSig.size() - 1))) {
+        return true;
     }
-    return true;
+    return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
 }
 
 bool CheckSignatureEncoding(const valtype &vchSig, uint32_t flags,