diff --git a/mock_cellular.h b/mock_cellular.h
index 8d0e4e8..a29358f 100644
--- a/mock_cellular.h
+++ b/mock_cellular.h
@@ -35,6 +35,7 @@
       const std::vector<std::string> &invalidated_properties));
   MOCK_METHOD1(set_modem_state, void(ModemState state));
   MOCK_METHOD0(DestroyService, void());
+  MOCK_METHOD1(StartPPP, void(const std::string &serial_device));
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockCellular);