diff --git a/js/src/threading/ExclusiveData.h b/js/src/threading/ExclusiveData.h
index edbe9dbc64..344fcc29fa 100644
--- a/js/src/threading/ExclusiveData.h
+++ b/js/src/threading/ExclusiveData.h
@@ -117,7 +117,7 @@ class ExclusiveData
     }
 
     ExclusiveData(ExclusiveData&& rhs) :
-      lock_(mozilla::Move(rhs.lock))
+      lock_(mozilla::Move(rhs.lock()))
     {
         MOZ_ASSERT(&rhs != this, "self-move disallowed!");
         new (value_.addr()) T(mozilla::Move(*rhs.value_.addr()));