diff --git a/python/src/trezorlib/debuglink.py b/python/src/trezorlib/debuglink.py
index 052fa3f2cf..889475dc6e 100644
--- a/python/src/trezorlib/debuglink.py
+++ b/python/src/trezorlib/debuglink.py
@@ -407,6 +407,9 @@ class TrezorClientDebugLink(TrezorClient):
 
         Useful for test scenarios with an active malicious actor on the wire.
         """
+        if not self.in_with_statement:
+            raise RuntimeError("Must be called inside 'with' statement")
+
         self.filters[message_type] = callback
 
     def _filter_message(self, msg):
@@ -477,6 +480,7 @@ class TrezorClientDebugLink(TrezorClient):
 
         self.in_with_statement -= 1
         self.ui.clear()
+        self.filters.clear()
         self.watch_layout(False)
 
         if _type is not None:
diff --git a/tests/device_tests/test_msg_signtx.py b/tests/device_tests/test_msg_signtx.py
index ddd709b4cf..b073495cab 100644
--- a/tests/device_tests/test_msg_signtx.py
+++ b/tests/device_tests/test_msg_signtx.py
@@ -826,12 +826,12 @@ class TestMsgSigntx:
 
             return msg
 
-        # Set up attack processors
-        client.set_filter(messages.TxAck, attack_processor)
-
-        with pytest.raises(
+        with client, pytest.raises(
             TrezorFailure, match="Transaction has changed during signing"
         ):
+            # Set up attack processors
+            client.set_filter(messages.TxAck, attack_processor)
+
             btc.sign_tx(
                 client,
                 "Bitcoin",
@@ -879,12 +879,12 @@ class TestMsgSigntx:
 
             return msg
 
-        # Set up attack processors
-        client.set_filter(messages.TxAck, attack_processor)
-
-        with pytest.raises(
+        with client, pytest.raises(
             TrezorFailure, match="Transaction has changed during signing"
         ):
+            # Set up attack processors
+            client.set_filter(messages.TxAck, attack_processor)
+
             btc.sign_tx(
                 client, "Testnet", [inp1], [out1, out2], prev_txes=TX_CACHE_TESTNET
             )
@@ -933,9 +933,9 @@ class TestMsgSigntx:
 
             return msg
 
-        client.set_filter(messages.TxAck, attack_processor)
         # Now run the attack, must trigger the exception
         with client:
+            client.set_filter(messages.TxAck, attack_processor)
             client.set_expected_responses(
                 [
                     request_input(0),
diff --git a/tests/device_tests/test_msg_signtx_bcash.py b/tests/device_tests/test_msg_signtx_bcash.py
index 6444773631..53f9edc9f6 100644
--- a/tests/device_tests/test_msg_signtx_bcash.py
+++ b/tests/device_tests/test_msg_signtx_bcash.py
@@ -230,9 +230,8 @@ class TestMsgSigntxBch:
 
             return msg
 
-        client.set_filter(proto.TxAck, attack_processor)
-
         with client:
+            client.set_filter(proto.TxAck, attack_processor)
             client.set_expected_responses(
                 [
                     request_input(0),
diff --git a/tests/device_tests/test_msg_signtx_bgold.py b/tests/device_tests/test_msg_signtx_bgold.py
index 727d5196cd..47340b0cbf 100644
--- a/tests/device_tests/test_msg_signtx_bgold.py
+++ b/tests/device_tests/test_msg_signtx_bgold.py
@@ -172,8 +172,8 @@ class TestMsgSigntxBitcoinGold:
 
             return msg
 
-        client.set_filter(proto.TxAck, attack_processor)
         with client:
+            client.set_filter(proto.TxAck, attack_processor)
             client.set_expected_responses(
                 [
                     request_input(0),
diff --git a/tests/device_tests/test_msg_signtx_segwit.py b/tests/device_tests/test_msg_signtx_segwit.py
index f990d8d6d4..e434f0d633 100644
--- a/tests/device_tests/test_msg_signtx_segwit.py
+++ b/tests/device_tests/test_msg_signtx_segwit.py
@@ -319,8 +319,8 @@ class TestMsgSigntxSegwit:
             return msg
 
         # Now run the attack, must trigger the exception
-        client.set_filter(proto.TxAck, attack_processor)
         with client:
+            client.set_filter(proto.TxAck, attack_processor)
             client.set_expected_responses(
                 [
                     request_input(0),
diff --git a/tests/device_tests/test_multisig.py b/tests/device_tests/test_multisig.py
index 4be213bfcc..d194bcefbf 100644
--- a/tests/device_tests/test_multisig.py
+++ b/tests/device_tests/test_multisig.py
@@ -294,8 +294,8 @@ class TestMultisig:
                 attack_count -= 1
             return msg
 
-        client.set_filter(proto.TxAck, attack_processor)
         with client:
+            client.set_filter(proto.TxAck, attack_processor)
             client.set_expected_responses(
                 [
                     request_input(0),