--- a/ipc/glue/Neutering.h
+++ b/ipc/glue/Neutering.h
@@ -44,28 +44,28 @@ private:
  * This class is analagous to MutexAutoUnlock for Mutex; it is an RAII class
  * that is to be instantiated within a NeuteredWindowRegion, thus temporarily
  * disabling neutering for the remainder of its enclosing block.
  * @see NeuteredWindowRegion
  */
 class MOZ_RAII DeneuteredWindowRegion
 {
 public:
-  DeneuteredWindowRegion(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM);
+  explicit DeneuteredWindowRegion(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM);
   ~DeneuteredWindowRegion();
 
 private:
   MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
   bool mReneuter;
 };
 
 class MOZ_RAII SuppressedNeuteringRegion
 {
 public:
-  SuppressedNeuteringRegion(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM);
+  explicit SuppressedNeuteringRegion(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM);
   ~SuppressedNeuteringRegion();
 
   static inline bool IsNeuteringSuppressed() { return sSuppressNeutering; }
 
 private:
   MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
   bool mReenable;