diff --git a/src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java b/src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java
index b8a6e29e..36598730 100644
--- a/src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java
+++ b/src/main/java/org/qortal/arbitrary/ArbitraryDataTransactionBuilder.java
@@ -217,7 +217,7 @@ public class ArbitraryDataTransactionBuilder {
             }
 
             final BaseTransactionData baseTransactionData = new BaseTransactionData(now, Group.NO_GROUP,
-                    lastReference, creatorPublicKey, BlockChain.getInstance().getUnitFee(), null);
+                    lastReference, creatorPublicKey, 0L, null);
             final int size = (int) arbitraryDataFile.size();
             final int version = 5;
             final int nonce = 0;
diff --git a/src/main/java/org/qortal/transaction/ArbitraryTransaction.java b/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
index d541563e..34adde9b 100644
--- a/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
+++ b/src/main/java/org/qortal/transaction/ArbitraryTransaction.java
@@ -73,6 +73,14 @@ public class ArbitraryTransaction extends Transaction {
 		this.arbitraryTransactionData.setNonce(MemoryPoW.compute2(transactionBytes, POW_BUFFER_SIZE, POW_DIFFICULTY));
 	}
 
+	@Override
+	public ValidationResult isFeeValid() throws DataException {
+		if (this.transactionData.getFee() < 0)
+			return ValidationResult.NEGATIVE_FEE;
+
+		return ValidationResult.OK;
+	}
+
 	@Override
 	public boolean hasValidReference() throws DataException {
 		// We shouldn't really get this far, but just in case: