diff --git a/tests/test_protocol.py b/tests/test_protocol.py
index 2ebd041..c4f1ae7 100644
--- a/tests/test_protocol.py
+++ b/tests/test_protocol.py
@@ -7,12 +7,14 @@
     Client,
     ClientEventAuthentication,
     ClientEventChannelsListed,
+    ClientEventIncompatibleVersion,
     ClientState,
     HighCommand,
     InvalidStateError,
     Protocol,
     Server,
     ServerEventAuthentication,
+    ServerEventIncompatibleVersion,
     ServerEventMessageReceived,
     ServerState,
 )
@@ -71,6 +73,33 @@ def test_authenticate():
     assert server_events == [ServerEventAuthentication(success=True, nick=nick)]
 
 
+def test_authenticate_incompatible_version():
+    hc = HighCommand()
+
+    nick = "thegamecracks"
+    client = Client(nick=nick)
+    server = Server(hc)
+
+    client.PROTOCOL_VERSION = server.PROTOCOL_VERSION + 1  # type: ignore
+    if client.PROTOCOL_VERSION > 255:
+        client.PROTOCOL_VERSION = server.PROTOCOL_VERSION - 1  # type: ignore
+
+    assert client.PROTOCOL_VERSION != server.PROTOCOL_VERSION
+
+    client_events, server_events = communicate(client, client.authenticate(), server)
+    assert client_events == [
+        ClientEventIncompatibleVersion(
+            client_version=client.PROTOCOL_VERSION,
+            server_version=server.PROTOCOL_VERSION,
+        )
+    ]
+    assert server_events == [
+        ServerEventIncompatibleVersion(
+            version=client.PROTOCOL_VERSION,
+        )
+    ]
+
+
 def test_send_message():
     nick = "thegamecracks"
     content = "Hello world!"