diff --git a/core/src/main/java/org/bitcoinj/core/GetUTXOsMessage.java b/core/src/main/java/org/bitcoinj/core/GetUTXOsMessage.java
index f4961c38..da177603 100644
--- a/core/src/main/java/org/bitcoinj/core/GetUTXOsMessage.java
+++ b/core/src/main/java/org/bitcoinj/core/GetUTXOsMessage.java
@@ -85,7 +85,7 @@ public class GetUTXOsMessage extends Message {
 
     @Override
     void bitcoinSerializeToStream(OutputStream stream) throws IOException {
-        stream.write(new byte[]{1});  // include mempool.
+        stream.write(new byte[]{includeMempool ? (byte) 1 : 0});  // include mempool.
         stream.write(new VarInt(outPoints.size()).encode());
         for (TransactionOutPoint outPoint : outPoints) {
             outPoint.bitcoinSerializeToStream(stream);