Index: src/Common/utility.h
===================================================================
--- src/Common/utility.h	(revision df00c78b128651274f61f1ce49367f7120e119e0)
+++ src/Common/utility.h	(revision a9762dce275b7241171979d7d5528dc795b1f283)
@@ -322,4 +322,6 @@
 
 	ValueGuardPtr(T * inRef) : old( inRef ? *inRef : T() ), ref(inRef) {}
+	ValueGuardPtr(const ValueGuardPtr& other) = delete;
+	ValueGuardPtr(ValueGuardPtr&& other) : old(other.old), ref(other.ref) { other.ref = nullptr; }
 	~ValueGuardPtr() { if( ref ) *ref = old; }
 };