diff --git a/src/main/java/org/qortal/transaction/ArbitraryTransaction.java b/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
index 9a11a820..ca5ce517 100644
--- a/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
+++ b/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
@@ -20,6 +20,7 @@ import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.arbitrary.ArbitraryDataFile;
 import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.ArbitraryTransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.utils.ArbitraryTransactionUtils;
@@ -90,8 +91,9 @@ public class ArbitraryTransaction extends Transaction {
 
 		// Disable reference checking after feature trigger timestamp
 		if (this.arbitraryTransactionData.getTimestamp() >= BlockChain.getInstance().getDisableReferenceTimestamp()) {
-			// Allow any non-null value
-			return this.arbitraryTransactionData.getReference() != null;
+			// Allow any value as long as it is the correct length
+			return this.arbitraryTransactionData.getReference() != null &&
+					this.arbitraryTransactionData.getReference().length == Transformer.SIGNATURE_LENGTH;
 		}
 
 		if (this.arbitraryTransactionData.getReference() == null) {
diff --git a/src/main/java/org/qortal/transaction/AtTransaction.java b/src/main/java/org/qortal/transaction/AtTransaction.java
index be0388a1..b07f006b 100644
--- a/src/main/java/org/qortal/transaction/AtTransaction.java
+++ b/src/main/java/org/qortal/transaction/AtTransaction.java
@@ -13,6 +13,7 @@ import org.qortal.data.transaction.TransactionData;
 import org.qortal.repository.DataException;
 import org.qortal.repository.Repository;
 import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.AtTransactionTransformer;
 import org.qortal.utils.Amounts;
 
@@ -78,8 +79,9 @@ public class AtTransaction extends Transaction {
 	public boolean hasValidReference() throws DataException {
 		// Disable reference checking after feature trigger timestamp
 		if (this.atTransactionData.getTimestamp() >= BlockChain.getInstance().getDisableReferenceTimestamp()) {
-			// Allow any non-null value
-			return this.atTransactionData.getReference() != null;
+			// Allow any value as long as it is the correct length
+			return this.atTransactionData.getReference() != null &&
+					this.atTransactionData.getReference().length == Transformer.SIGNATURE_LENGTH;
 		}
 
 		// Check reference is correct, using AT account, not transaction creator which is null account
diff --git a/src/main/java/org/qortal/transaction/MessageTransaction.java b/src/main/java/org/qortal/transaction/MessageTransaction.java
index 4540bea6..a9d3a01c 100644
--- a/src/main/java/org/qortal/transaction/MessageTransaction.java
+++ b/src/main/java/org/qortal/transaction/MessageTransaction.java
@@ -21,6 +21,7 @@ import org.qortal.repository.DataException;
 import org.qortal.repository.GroupRepository;
 import org.qortal.repository.Repository;
 import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.ChatTransactionTransformer;
 import org.qortal.transform.transaction.MessageTransactionTransformer;
 import org.qortal.transform.transaction.TransactionTransformer;
@@ -167,8 +168,9 @@ public class MessageTransaction extends Transaction {
 
 		// Disable reference checking after feature trigger timestamp
 		if (this.messageTransactionData.getTimestamp() >= BlockChain.getInstance().getDisableReferenceTimestamp()) {
-			// Allow any non-null value
-			return this.messageTransactionData.getReference() != null;
+			// Allow any value as long as it is the correct length
+			return this.messageTransactionData.getReference() != null &&
+					this.messageTransactionData.getReference().length == Transformer.SIGNATURE_LENGTH;
 		}
 
 		if (this.messageTransactionData.getReference() == null)
diff --git a/src/main/java/org/qortal/transaction/Transaction.java b/src/main/java/org/qortal/transaction/Transaction.java
index 9f56af6b..b56d48cf 100644
--- a/src/main/java/org/qortal/transaction/Transaction.java
+++ b/src/main/java/org/qortal/transaction/Transaction.java
@@ -31,6 +31,7 @@ import org.qortal.repository.GroupRepository;
 import org.qortal.repository.Repository;
 import org.qortal.settings.Settings;
 import org.qortal.transform.TransformationException;
+import org.qortal.transform.Transformer;
 import org.qortal.transform.transaction.TransactionTransformer;
 import org.qortal.utils.NTP;
 
@@ -907,8 +908,9 @@ public abstract class Transaction {
 	public boolean hasValidReference() throws DataException {
 		// Disable reference checking after feature trigger timestamp
 		if (this.transactionData.getTimestamp() >= BlockChain.getInstance().getDisableReferenceTimestamp()) {
-			// Allow any non-null value
-			return this.transactionData.getReference() != null;
+			// Allow any value as long as it is the correct length
+			return this.transactionData.getReference() != null &&
+					this.transactionData.getReference().length == Transformer.SIGNATURE_LENGTH;
 		}
 
 		Account creator = getCreator();
diff --git a/src/test/java/org/qortal/test/TransactionReferenceTests.java b/src/test/java/org/qortal/test/TransactionReferenceTests.java
index 32a8da82..fdff8b59 100644
--- a/src/test/java/org/qortal/test/TransactionReferenceTests.java
+++ b/src/test/java/org/qortal/test/TransactionReferenceTests.java
@@ -122,16 +122,43 @@ public class TransactionReferenceTests extends Common {
             TransactionData paymentTransactionData = new PaymentTransactionData(TestTransaction.generateBase(alice), recipient.getAddress(), 100000L);
 
             // Set a 1-byte reference
-            byte[] randomByte = new byte[1];
+            byte[] randomByte = new byte[63];
             random.nextBytes(randomByte);
             paymentTransactionData.setReference(randomByte);
 
             Transaction paymentTransaction = Transaction.fromData(repository, paymentTransactionData);
 
-            // Transaction should be valid, as any non-null value is allowed
+            // Transaction should be invalid, as reference isn't long enough
             Transaction.ValidationResult validationResult = paymentTransaction.isValidUnconfirmed();
-            assertEquals(Transaction.ValidationResult.OK, validationResult);
-            TransactionUtils.signAndImportValid(repository, paymentTransactionData, alice);
+            assertEquals(Transaction.ValidationResult.INVALID_REFERENCE, validationResult);
+        }
+    }
+
+    @Test
+    public void testLongReferenceAfterFeatureTrigger() throws DataException {
+        Common.useSettings("test-settings-v2-disable-reference.json");
+        Random random = new Random();
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            PrivateKeyAccount alice = Common.getTestAccount(repository, "alice");
+
+            byte[] randomPrivateKey = new byte[32];
+            random.nextBytes(randomPrivateKey);
+            PrivateKeyAccount recipient = new PrivateKeyAccount(repository, randomPrivateKey);
+
+            // Create payment transaction data
+            TransactionData paymentTransactionData = new PaymentTransactionData(TestTransaction.generateBase(alice), recipient.getAddress(), 100000L);
+
+            // Set a 1-byte reference
+            byte[] randomByte = new byte[65];
+            random.nextBytes(randomByte);
+            paymentTransactionData.setReference(randomByte);
+
+            Transaction paymentTransaction = Transaction.fromData(repository, paymentTransactionData);
+
+            // Transaction should be invalid, as reference is too long
+            Transaction.ValidationResult validationResult = paymentTransaction.isValidUnconfirmed();
+            assertEquals(Transaction.ValidationResult.INVALID_REFERENCE, validationResult);
         }
     }