diff --git a/aegisub/libaegisub/include/libaegisub/scoped_ptr.h b/aegisub/libaegisub/include/libaegisub/scoped_ptr.h
index 249f01f8f..83cba68af 100644
--- a/aegisub/libaegisub/include/libaegisub/scoped_ptr.h
+++ b/aegisub/libaegisub/include/libaegisub/scoped_ptr.h
@@ -33,12 +33,15 @@ class scoped_ptr {
 	T* ptr;
 	scoped_ptr(scoped_ptr const&);
 	scoped_ptr& operator=(scoped_ptr const&);
+
+	typedef T *scoped_ptr<T>::*unspecified_bool_type;
 public:
 	typedef T element_type;
 
 	T& operator*() const {return *ptr; }
 	T* operator->() const { return ptr; }
 	T* get() const { return ptr; }
+	operator unspecified_bool_type() const { return ptr ? &scoped_ptr<T>::ptr : 0; }
 
 	void reset(T *p = 0) {
 		delete ptr;