diff --git a/gittensor/validator/pat_handler.py b/gittensor/validator/pat_handler.py
index 7b9f6aa7..ea73dcf6 100644
--- a/gittensor/validator/pat_handler.py
+++ b/gittensor/validator/pat_handler.py
@@ -101,6 +101,14 @@ async def priority_pat_broadcast(validator: 'Validator', synapse: PatBroadcastSy
 async def handle_pat_check(validator: 'Validator', synapse: PatCheckSynapse) -> PatCheckSynapse:
     """Check if the validator has the miner's PAT stored and re-validate it."""
     hotkey = _get_hotkey(synapse)
+
+    if hotkey not in validator.metagraph.hotkeys:
+        synapse.has_pat = False
+        synapse.pat_valid = False
+        synapse.rejection_reason = 'Hotkey not registered on subnet'
+        bt.logging.warning(f'PAT check rejected — hotkey {hotkey[:16]}... not registered')
+        return synapse
+
     uid = validator.metagraph.hotkeys.index(hotkey)
     entry = pat_storage.get_pat_by_uid(uid)
 
diff --git a/tests/validator/test_pat_handler.py b/tests/validator/test_pat_handler.py
index 49839bdb..ad9ebfe3 100644
--- a/tests/validator/test_pat_handler.py
+++ b/tests/validator/test_pat_handler.py
@@ -223,3 +223,11 @@ def test_stored_but_invalid_pat(self, mock_validate, mock_test_query, mock_valid
         assert result.has_pat is True
         assert result.pat_valid is False
         assert 'PAT expired' in (result.rejection_reason or '')
+
+    def test_unregistered_hotkey_returns_no_pat(self, mock_validator):
+        """handle_pat_check must not raise ValueError for unregistered hotkeys."""
+        synapse = _make_check_synapse('unknown_hotkey')
+        result = _run(handle_pat_check(mock_validator, synapse))
+        assert result.has_pat is False
+        assert result.pat_valid is False
+        assert 'not registered' in (result.rejection_reason or '').lower()