diff --git a/core/tests/test_trezor.wire.thp_v1.py b/core/tests/test_trezor.wire.thp_v1.py
index a3120d43e..a2ffb2aec 100644
--- a/core/tests/test_trezor.wire.thp_v1.py
+++ b/core/tests/test_trezor.wire.thp_v1.py
@@ -67,7 +67,7 @@ def printBytes(a):
 def getPlaintext() -> bytes:
     if THP.sync_get_receive_expected_bit(THP.get_active_session()) == 1:
         return PLAINTEXT_1
-    PLAINTEXT_0
+    return PLAINTEXT_0
 
 
 def getCid() -> int:
@@ -97,7 +97,6 @@ class TestWireTrezorHostProtocolV1(unittest.TestCase):
         )
 
         buffer = bytearray(64)
-        printBytes(cid_req_message)
         gen = thp_v1.read_message(self.interface, buffer)
         query = gen.send(None)
         self.assertObjectEqual(query, self.interface.wait_object(io.POLL_READ))
@@ -219,6 +218,32 @@ class TestWireTrezorHostProtocolV1(unittest.TestCase):
         # read should have allocated its own buffer and not touch ours
         self.assertEqual(buffer, b"\x00")
 
+    def test_roundtrip(self):
+        message_payload = bytes(range(256))
+        message = MessageWithId(
+            MESSAGE_TYPE, message_payload, THP._get_id(self.interface, COMMON_CID)
+        )
+        gen = thp_v1.write_message(self.interface, message)
+        # exhaust the iterator:
+        # (XXX we can only do this because the iterator is only accepting None and returns None)
+        for query in gen:
+            self.assertObjectEqual(query, self.interface.wait_object(io.POLL_WRITE))
+
+        buffer = bytearray(1024)
+        gen = thp_v1.read_message(self.interface, buffer)
+        query = gen.send(None)
+        for packet in self.interface.data:
+            self.assertObjectEqual(query, self.interface.wait_object(io.POLL_READ))
+            printBytes(packet)
+            query = gen.send(packet)
+
+        with self.assertRaises(StopIteration) as e:
+            gen.send(None)
+
+        result = e.value.value
+        self.assertEqual(result.type, MESSAGE_TYPE)
+        self.assertEqual(result.data, message.data)
+
     def test_write_one_packet(self):
         message = MessageWithId(
             MESSAGE_TYPE, b"", THP._get_id(self.interface, COMMON_CID)
@@ -231,7 +256,7 @@ class TestWireTrezorHostProtocolV1(unittest.TestCase):
             gen.send(None)
 
         header = make_header(
-            PLAINTEXT_0, COMMON_CID, _MESSAGE_TYPE_LEN + CHECKSUM_LENGTH
+            getPlaintext(), COMMON_CID, _MESSAGE_TYPE_LEN + CHECKSUM_LENGTH
         )
         expected_message = (
             header
@@ -285,32 +310,6 @@ class TestWireTrezorHostProtocolV1(unittest.TestCase):
         last_packet = packets[-1] + packets[-2][len(packets[-1]) :]
         self.assertEqual(last_packet, self.interface.data[-1])
 
-    def test_roundtrip(self):
-        message_payload = bytes(range(256))
-        message = MessageWithId(
-            MESSAGE_TYPE, message_payload, THP._get_id(self.interface, COMMON_CID)
-        )
-        gen = thp_v1.write_message(self.interface, message)
-
-        # exhaust the iterator:
-        # (XXX we can only do this because the iterator is only accepting None and returns None)
-        for query in gen:
-            self.assertObjectEqual(query, self.interface.wait_object(io.POLL_WRITE))
-
-        buffer = bytearray(1024)
-        gen = thp_v1.read_message(self.interface, buffer)
-        query = gen.send(None)
-        for packet in self.interface.data:
-            self.assertObjectEqual(query, self.interface.wait_object(io.POLL_READ))
-            query = gen.send(packet)
-
-        with self.assertRaises(StopIteration) as e:
-            gen.send(None)
-
-        result = e.value.value
-        self.assertEqual(result.type, MESSAGE_TYPE)
-        self.assertEqual(result.data, message.data)
-
     def test_read_huge_packet(self):
         PACKET_COUNT = 1180
         # message that takes up 1 180 USB packets