diff --git a/src/dep/include/zthread/Guard.h b/src/dep/include/zthread/Guard.h
index af414f23..5a3f6031 100644
--- a/src/dep/include/zthread/Guard.h
+++ b/src/dep/include/zthread/Guard.h
@@ -428,7 +428,7 @@ class Guard : private LockHolder<LockType>, private NonCopyable {
   template <class U, class V>
   Guard(Guard<U, V>& g) : LockHolder<LockType>(g) {
 
-    LockingPolicy::shareScope(*this, extract(g));
+    LockingPolicy::shareScope(*this, this->extract(g));
 
   }