diff --git a/protocol/src/main/kotlin/org/openrs2/protocol/js5/Js5ResponseEncoder.kt b/protocol/src/main/kotlin/org/openrs2/protocol/js5/Js5ResponseEncoder.kt
index 94c55dab..d2650ef1 100644
--- a/protocol/src/main/kotlin/org/openrs2/protocol/js5/Js5ResponseEncoder.kt
+++ b/protocol/src/main/kotlin/org/openrs2/protocol/js5/Js5ResponseEncoder.kt
@@ -20,7 +20,7 @@ public object Js5ResponseEncoder : MessageToByteEncoder<Js5Response>(Js5Response
 
         var compression = msg.data.readUnsignedByte().toInt()
         if (msg.prefetch) {
-            compression = compression xor 0x80
+            compression = compression or 0x80
         }
         out.writeByte(compression)