diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index a746fde29c..c3eaf8b310 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -76,14 +76,15 @@ bool IsStandardTx(const CTransaction& tx, bool permit_bare_multisig, const CFeeR
 
     for (const CTxIn& txin : tx.vin)
     {
-        // Biggest 'standard' txin is a 15-of-15 P2SH multisig with compressed
-        // keys (remember the 520 byte limit on redeemScript size). That works
-        // out to a (15*(33+1))+3=513 byte redeemScript, 513+1+15*(73+1)+3=1627
-        // bytes of scriptSig, which we round off to 1650 bytes for some minor
-        // future-proofing. That's also enough to spend a 20-of-20
-        // CHECKMULTISIG scriptPubKey, though such a scriptPubKey is not
-        // considered standard.
-        if (txin.scriptSig.size() > 1650) {
+        // Biggest 'standard' txin involving only keys is a 15-of-15 P2SH
+        // multisig with compressed keys (remember the 520 byte limit on
+        // redeemScript size). That works out to a (15*(33+1))+3=513 byte
+        // redeemScript, 513+1+15*(73+1)+3=1627 bytes of scriptSig, which
+        // we round off to 1650(MAX_STANDARD_SCRIPTSIG_SIZE) bytes for
+        // some minor future-proofing. That's also enough to spend a
+        // 20-of-20 CHECKMULTISIG scriptPubKey, though such a scriptPubKey
+        // is not considered standard.
+        if (txin.scriptSig.size() > MAX_STANDARD_SCRIPTSIG_SIZE) {
             reason = "scriptsig-size";
             return false;
         }
diff --git a/src/policy/policy.h b/src/policy/policy.h
index 196a3faef0..881bc95454 100644
--- a/src/policy/policy.h
+++ b/src/policy/policy.h
@@ -36,6 +36,8 @@ static const unsigned int DEFAULT_INCREMENTAL_RELAY_FEE = 1000;
 static const unsigned int DEFAULT_BYTES_PER_SIGOP = 20;
 /** Default for -permitbaremultisig */
 static const bool DEFAULT_PERMIT_BAREMULTISIG = true;
+/** The maximum size of a standard ScriptSig */
+static const unsigned int MAX_STANDARD_SCRIPTSIG_SIZE = 1650;
 /** Min feerate for defining dust. Historically this has been based on the
  * minRelayTxFee, however changing the dust limit changes which transactions are
  * standard and should be done with care and ideally rarely. It makes sense to