diff --git a/src/ripple/app/tx/impl/Transactor.cpp b/src/ripple/app/tx/impl/Transactor.cpp
index a6df144c2..55b19ddd0 100644
--- a/src/ripple/app/tx/impl/Transactor.cpp
+++ b/src/ripple/app/tx/impl/Transactor.cpp
@@ -1015,7 +1015,7 @@ Transactor::checkMultiSign(PreclaimContext const& ctx)
         if (!allowedSigners)
             return allowedSigners.error();
 
-        // Build lookup map for O(1) signer validation and weight retrieval
+        // Build lookup map for signer validation and weight retrieval
         std::map<AccountID, uint16_t> signerWeights;
         uint32_t totalWeight{0}, cyclicWeight{0};
         for (auto const& entry : *allowedSigners)
diff --git a/src/test/app/MultiSign_test.cpp b/src/test/app/MultiSign_test.cpp
index 51bff953f..1c1611ab9 100644
--- a/src/test/app/MultiSign_test.cpp
+++ b/src/test/app/MultiSign_test.cpp
@@ -1466,7 +1466,7 @@ public:
         // Leaf signer: set Account + SigningPubKey + TxnSignature
         {
             STObject signer(sfSigner);
-            signer.setAccountID(sfAccount, AccountID{1});
+            signer.setAccountID(sfAccount, bogie.id());
             signer.setFieldVL(sfSigningPubKey, Blob(33, 0x02));
             signer.setFieldVL(sfTxnSignature, Blob(64, 0xAA));
             signer.applyTemplateFromSField(sfSigner);
@@ -1487,7 +1487,7 @@ public:
         // Nested signer: set Account + Signers
         {
             STObject signer(sfSigner);
-            signer.setAccountID(sfAccount, AccountID{2});
+            signer.setAccountID(sfAccount, demon.id());
             signer.setFieldArray(sfSigners, STArray{});
             signer.applyTemplateFromSField(sfSigner);
 
@@ -1504,7 +1504,7 @@ public:
         // Invalid: all 4 fields set (both leaf and nested fields)
         {
             STObject signer(sfSigner);
-            signer.setAccountID(sfAccount, AccountID{3});
+            signer.setAccountID(sfAccount, ghost.id());
             signer.setFieldVL(sfSigningPubKey, Blob(33, 0x02));
             signer.setFieldVL(sfTxnSignature, Blob(64, 0xAA));
             signer.setFieldArray(sfSigners, STArray{});
diff --git a/src/test/protocol/STTx_test.cpp b/src/test/protocol/STTx_test.cpp
index be818ec7b..a11bcde36 100644
--- a/src/test/protocol/STTx_test.cpp
+++ b/src/test/protocol/STTx_test.cpp
@@ -1793,14 +1793,23 @@ public:
             testMalformedSigningAccount(soTest1, true);
         }
 
-        /*{ // RHNOTE: featureNestedMultiSign covers this in the
-        checkMultiSign()
+        {
             // Test case 2.  Omit sfSigningPubKey from SigningAccount.
+            // With featureNestedMultiSign, sfSigningPubKey is optional in the
+            // template so serialization succeeds. But the validation layer
+            // (isValidSignerEntry) correctly rejects {Account + TxnSignature}
+            // as neither a valid leaf nor nested signer.
             STObject soTest2(sfSigner);
             soTest2.setAccountID(sfAccount, id2);
             soTest2.setFieldVL(sfTxnSignature, saMultiSignature);
-            testMalformedSigningAccount(soTest2, false);
-        }*/
+            testMalformedSigningAccount(soTest2, true);  // serializes OK now
+
+            // But validation-layer helpers reject it
+            soTest2.applyTemplateFromSField(sfSigner);
+            BEAST_EXPECT(!isLeafSigner(soTest2));
+            BEAST_EXPECT(!isNestedSigner(soTest2));
+            BEAST_EXPECT(!isValidSignerEntry(soTest2));
+        }
         {
             // Test case 3.  Extra sfAmount in SigningAccount.
             STObject soTest3(sfSigner);