diff --git a/mock_system_state.h b/mock_system_state.h
index bb6ee98..2b17ce4 100644
--- a/mock_system_state.h
+++ b/mock_system_state.h
@@ -10,6 +10,7 @@
 #include <metrics/metrics_library_mock.h>
 #include <policy/mock_device_policy.h>
 
+#include "update_engine/mock_gpio_handler.h"
 #include "update_engine/mock_payload_state.h"
 #include "update_engine/prefs_mock.h"
 #include "update_engine/system_state.h"
@@ -20,49 +21,56 @@
 // OOBE is completed even when there's no such marker file, etc.
 class MockSystemState : public SystemState {
  public:
-  MockSystemState() : prefs_(&mock_prefs_) {
+  inline MockSystemState() : prefs_(&mock_prefs_) {
     mock_payload_state_.Initialize(&mock_prefs_);
+    mock_gpio_handler_ = new testing::NiceMock<MockGpioHandler>();
   }
-  virtual ~MockSystemState() {}
+  inline virtual ~MockSystemState() {
+    delete mock_gpio_handler_;
+  }
 
   MOCK_METHOD0(IsOOBEComplete, bool());
   MOCK_METHOD1(set_device_policy, void(const policy::DevicePolicy*));
   MOCK_CONST_METHOD0(device_policy, const policy::DevicePolicy*());
 
-  virtual ConnectionManager* connection_manager() {
+  inline virtual ConnectionManager* connection_manager() {
     return connection_manager_;
   }
 
-  virtual MetricsLibraryInterface* metrics_lib() {
+  inline virtual MetricsLibraryInterface* metrics_lib() {
     return &mock_metrics_lib_;
   }
 
-  virtual PrefsInterface* prefs() {
+  inline virtual PrefsInterface* prefs() {
     return prefs_;
   }
 
-  virtual PayloadStateInterface* payload_state() {
+  inline virtual PayloadStateInterface* payload_state() {
     return &mock_payload_state_;
   }
 
+  inline virtual GpioHandler* gpio_handler() const {
+    return mock_gpio_handler_;
+  }
+
   // MockSystemState-specific public method.
-  void set_connection_manager(ConnectionManager* connection_manager) {
+  inline void set_connection_manager(ConnectionManager* connection_manager) {
     connection_manager_ = connection_manager;
   }
 
-  MetricsLibraryMock* mock_metrics_lib() {
+  inline MetricsLibraryMock* mock_metrics_lib() {
     return &mock_metrics_lib_;
   }
 
-  void set_prefs(PrefsInterface* prefs) {
+  inline void set_prefs(PrefsInterface* prefs) {
     prefs_ = prefs;
   }
 
-  testing::NiceMock<PrefsMock> *mock_prefs() {
+  inline testing::NiceMock<PrefsMock> *mock_prefs() {
     return &mock_prefs_;
   }
 
-  MockPayloadState* mock_payload_state() {
+  inline MockPayloadState* mock_payload_state() {
     return &mock_payload_state_;
   }
 
@@ -71,6 +79,7 @@
   MetricsLibraryMock mock_metrics_lib_;
   testing::NiceMock<PrefsMock> mock_prefs_;
   testing::NiceMock<MockPayloadState> mock_payload_state_;
+  testing::NiceMock<MockGpioHandler>* mock_gpio_handler_;
 
   // These are pointers to objects which caller can override.
   PrefsInterface* prefs_;