diff --git a/src/core/object.cc b/src/core/object.cc
index d00eba047..0135fcfdc 100644
--- a/src/core/object.cc
+++ b/src/core/object.cc
@@ -273,7 +273,7 @@ InterfaceId::GetRegisteredN (void)
 InterfaceId 
 InterfaceId::GetRegistered (uint32_t i)
 {
-  return Singleton<IidManager>::Get ()->GetRegistered (i);
+  return InterfaceId (Singleton<IidManager>::Get ()->GetRegistered (i));
 }
 
 InterfaceId 
diff --git a/src/core/object.h b/src/core/object.h
index a897d040a..861337862 100644
--- a/src/core/object.h
+++ b/src/core/object.h
@@ -103,7 +103,7 @@ private:
   friend bool operator == (InterfaceId a, InterfaceId b);
   friend bool operator != (InterfaceId a, InterfaceId b);
 
-  InterfaceId (uint16_t iid);
+  explicit InterfaceId (uint16_t iid);
   void DoAddConstructor (CallbackBase callback, uint32_t nArguments);
   CallbackBase LookupConstructor (uint32_t nArguments);