diff --git a/common/fake_prefs.h b/common/fake_prefs.h
index b1c5b71..b24ff4d 100644
--- a/common/fake_prefs.h
+++ b/common/fake_prefs.h
@@ -49,6 +49,9 @@
   bool Exists(const std::string& key) const override;
   bool Delete(const std::string& key) override;
 
+  bool GetSubKeys(const std::string& ns,
+                  std::vector<std::string>* keys) const override;
+
   void AddObserver(const std::string& key,
                    ObserverInterface* observer) override;
   void RemoveObserver(const std::string& key,