diff --git a/master/buildbot/test/unit/test_worker_protocols_pb.py b/master/buildbot/test/unit/test_worker_protocols_pb.py
index 95af65fc1ce..5c8b9b6664c 100644
--- a/master/buildbot/test/unit/test_worker_protocols_pb.py
+++ b/master/buildbot/test/unit/test_worker_protocols_pb.py
@@ -157,9 +157,12 @@ def side_effect(*args, **kwargs):
         self.assertEqual(info, r)
         calls = [
             mock.call('getWorkerInfo'),
+            mock.call('print',
+                      message='buildbot-slave detected, failing back to deprecated buildslave API. '
+                              '(Ignoring missing getWorkerInfo method.)'),
             mock.call('getSlaveInfo'),
             mock.call('getCommands'),
-            mock.call('getVersion')
+            mock.call('getVersion'),
         ]
         self.mind.callRemote.assert_has_calls(calls)
 
@@ -191,6 +194,9 @@ def side_effect(*args, **kwargs):
         self.assertEqual(info, r)
         calls = [
             mock.call('getWorkerInfo'),
+            mock.call('print',
+                      message='buildbot-slave detected, failing back to deprecated buildslave API. '
+                              '(Ignoring missing getWorkerInfo method.)'),
             mock.call('getSlaveInfo'),
         ]
         self.mind.callRemote.assert_has_calls(calls)
@@ -253,6 +259,8 @@ def test_remoteGetWorkerInfo_no_info(self):
         # All remote commands tried in remoteGetWorkerInfo are unavailable.
         # This should be real old worker...
         def side_effect(*args, **kwargs):
+            if args[0] == 'print':
+                return
             return defer.fail(twisted_pb.RemoteError(
                 'twisted.spread.flavors.NoSuchMethod', None, None))
 
@@ -264,6 +272,9 @@ def side_effect(*args, **kwargs):
         self.assertEqual(info, r)
         calls = [
             mock.call('getWorkerInfo'),
+            mock.call('print',
+                      message='buildbot-slave detected, failing back to deprecated buildslave API. '
+                              '(Ignoring missing getWorkerInfo method.)'),
             mock.call('getSlaveInfo'),
             mock.call('getCommands'),
             mock.call('getVersion'),
diff --git a/master/buildbot/worker/protocols/pb.py b/master/buildbot/worker/protocols/pb.py
index 4aeeec4641e..170fc9750c0 100644
--- a/master/buildbot/worker/protocols/pb.py
+++ b/master/buildbot/worker/protocols/pb.py
@@ -198,6 +198,9 @@ def remoteGetWorkerInfo(self):
                 info = yield self.mind.callRemote('getWorkerInfo')
             defer.returnValue(info)
         except _NoSuchMethod:
+            yield self.remotePrint(
+                "buildbot-slave detected, failing back to deprecated buildslave API. "
+                "(Ignoring missing getWorkerInfo method.)")
             info = {}
 
             # Probably this is deprecated buildslave.