diff --git a/openttd_protocol/wire/tcp.py b/openttd_protocol/wire/tcp.py
index 5281692..2b2df27 100644
--- a/openttd_protocol/wire/tcp.py
+++ b/openttd_protocol/wire/tcp.py
@@ -92,16 +92,23 @@ def _detect_source_ip_port(self, data):
 
         # This message arrived via the proxy protocol; use the information
         # from this to figure out the real ip and port.
-        proxy_end = data.find(b"\r\n")
-        proxy = data[0:proxy_end].decode()
-        data = data[proxy_end + 2 :]
-
         # Example how 'proxy' looks:
         #  PROXY TCP4 127.0.0.1 127.0.0.1 33487 12345
 
+        # Search for \r\n, marking the end of the proxy protocol header.
+        for i in range(len(data) - 1):
+            if data[i] == 13 and data[i + 1] == 10:
+                proxy_end = i
+                break
+        else:
+            log.warning("Receive proxy protocol header without end from %s:%d", self.source.ip, self.source.port)
+            return data
+
+        proxy = data[0:proxy_end].tobytes().decode()
         (_, _, ip, _, port, _) = proxy.split(" ")
         self.source = Source(self, self.source.addr, ip, int(port))
-        return data
+
+        return data[proxy_end + 2 :]
 
     def data_received(self, data):
         data = memoryview(data)
diff --git a/openttd_protocol/wire/test_tcp.py b/openttd_protocol/wire/test_tcp.py
index b8e25c9..fe34bb7 100644
--- a/openttd_protocol/wire/test_tcp.py
+++ b/openttd_protocol/wire/test_tcp.py
@@ -56,7 +56,7 @@ async def test_detect_source_ip_port(proxy_protocol, data, result, ip, port):
     test.source = Source(test, None, "127.0.0.2", 54321)
     test.proxy_protocol = proxy_protocol
 
-    assert test._detect_source_ip_port(data) == result
+    assert test._detect_source_ip_port(memoryview(data)) == result
     assert str(test.source.ip) == ip
     assert test.source.port == port
 
@@ -74,7 +74,7 @@ async def test_data_received(data, data_left, result):
     test = OpenTTDProtocolTest(None)
     test.task.cancel()
 
-    test.data_received(data)
+    test.data_received(memoryview(data))
     assert test._data == data_left
     try:
         assert test._queue.get_nowait() == result
@@ -94,7 +94,7 @@ async def test_receive_packet(data, result):
     test = OpenTTDProtocolTest(None)
     test.task.cancel()
 
-    assert test.receive_packet(None, data) == result
+    assert test.receive_packet(None, memoryview(data)) == result
 
 
 @pytest.mark.parametrize(
@@ -112,7 +112,7 @@ async def test_receive_packet_failure(data, failure):
     test.task.cancel()
 
     with pytest.raises(failure):
-        test.receive_packet(None, data)
+        test.receive_packet(None, memoryview(data))
 
 
 @pytest.mark.parametrize(
@@ -141,7 +141,7 @@ async def receive_PACKET_TWO(source, **kwargs):
     test.source = Source(test, None, "127.0.0.1", 12345)
     test.transport = FakeTransport()
 
-    test._queue.put_nowait(data)
-    test._queue.put_nowait(b"\x04\x00\x00")  # Force an exception
+    test._queue.put_nowait(memoryview(data))
+    test._queue.put_nowait(memoryview(b"\x04\x00\x00"))  # Force an exception
     await test._process_queue()
     assert seen_packet[0] is True