diff --git a/tests/test_protect_call.py b/tests/test_protect_call.py
index 03c662bdc..db32a2f42 100644
--- a/tests/test_protect_call.py
+++ b/tests/test_protect_call.py
@@ -26,6 +26,10 @@ class TestProtectCall(common.TrezorTest):
     def test_incorrect_pin(self):
         self.client.setup_debuglink(button=True, pin_correct=False)
         self.assertRaises(PinException, self._some_protected_call)
+
+    def test_cancelled_pin(self):
+        self.client.setup_debuglink(button=True, pin_correct=-1)  # PIN cancel
+        self.assertRaises(PinException, self._some_protected_call)
         
 if __name__ == '__main__':
     unittest.main()
diff --git a/trezorlib/client.py b/trezorlib/client.py
index f24b7a0aa..ccb058c53 100644
--- a/trezorlib/client.py
+++ b/trezorlib/client.py
@@ -102,11 +102,14 @@ class TrezorClient(object):
                        
             if isinstance(resp, proto.PinMatrixRequest):
                 if self.debuglink:
-                    if self.debug_pin:
+                    if self.debug_pin == 1:
                         pin = self.debuglink.read_pin_encoded()
                         msg2 = proto.PinMatrixAck(pin=pin)
+                    elif self.debug_pin == -1:
+                        msg2 = proto.PinMatrixCancel()
                     else:
                         msg2 = proto.PinMatrixAck(pin='444444222222')
+
                 else:
                     pin = self.pin_func("PIN required: ", resp.message)
                     msg2 = proto.PinMatrixAck(pin=pin)
@@ -118,7 +121,7 @@ class TrezorClient(object):
         
         if isinstance(resp, proto.Failure):
             self.message_func(resp.message)
-            
+
             if resp.code == 4:    
                 raise CallException("Action cancelled by user")