diff --git a/app/src/main/java/app/attestation/auditor/AttestationProtocol.java b/app/src/main/java/app/attestation/auditor/AttestationProtocol.java
index cb618135..b7dfabab 100644
--- a/app/src/main/java/app/attestation/auditor/AttestationProtocol.java
+++ b/app/src/main/java/app/attestation/auditor/AttestationProtocol.java
@@ -198,7 +198,7 @@ class AttestationProtocol {
     // the outer signature and the rest of the chain for pinning the expected chain. It enforces
     // downgrade protection for the OS version/patch (bootloader/TEE enforced) and app version (OS
     // enforced) by keeping them updated.
-    private static final byte PROTOCOL_VERSION = 5;
+    private static final byte PROTOCOL_VERSION = 6;
     private static final byte PROTOCOL_VERSION_MINIMUM = 5;
     // can become longer in the future, but this is the minimum length
     static final byte CHALLENGE_MESSAGE_LENGTH = 1 + RANDOM_TOKEN_LENGTH * 2;