diff --git a/lib/pos_fee_estimator.go b/lib/pos_fee_estimator.go
index e95aa2e55..aa20acd67 100644
--- a/lib/pos_fee_estimator.go
+++ b/lib/pos_fee_estimator.go
@@ -222,7 +222,7 @@ func addBlockToTransactionRegister(txnRegister *TransactionRegister, block *Cach
 		if txn.Tx.TxnMeta.GetTxnType() == TxnTypeBlockReward {
 			continue
 		}
-
+		txn.SetValidated(true)
 		if err := txnRegister.AddTransaction(txn); err != nil {
 			return errors.Wrap(err,
 				"PoSFeeEstimator.addBlockToTransactionRegister: error adding txn to pastBlocksTransactionRegister")
@@ -670,6 +670,10 @@ func (posFeeEstimator *PoSFeeEstimator) estimateFeeRateNanosPerKBGivenTransactio
 		if !ok {
 			break
 		}
+		// Skip transactions that aren't validated.
+		if !tx.IsValidated() {
+			continue
+		}
 		totalTxnsSize += tx.TxSizeBytes
 		txns = append(txns, tx)
 		if totalTxnsSize > maxSizeOfNumBlocks {