diff --git a/buffet/storage_impls.h b/buffet/storage_impls.h
index 04d5f0f..6e69084 100644
--- a/buffet/storage_impls.h
+++ b/buffet/storage_impls.h
@@ -16,7 +16,7 @@
 // Persists the given Value to an atomically written file.
 class FileStorage : public StorageInterface {
  public:
-  FileStorage(const base::FilePath& file_path);
+  explicit FileStorage(const base::FilePath& file_path);
   virtual ~FileStorage() = default;
   virtual std::unique_ptr<base::Value> Load() override;
   virtual bool Save(const base::Value* config) override;