diff --git a/src/mdn/MDNHelper.cpp b/src/mdn/MDNHelper.cpp
index 62028a12..640cda45 100644
--- a/src/mdn/MDNHelper.cpp
+++ b/src/mdn/MDNHelper.cpp
@@ -100,7 +100,7 @@ receivedMDNInfos MDNHelper::getReceivedMDN(const ref <const message> msg)
 
 const bool MDNHelper::needConfirmation(const ref <const message> msg)
 {
-	const header* hdr = msg->getHeader();
+	ref <const header> hdr = msg->getHeader();
 
 	// No "Return-Path" field
 	if (!hdr->hasField(fields::RETURN_PATH))
diff --git a/src/messaging/imap/IMAPMessage.cpp b/src/messaging/imap/IMAPMessage.cpp
index 97aa2d28..92ec675f 100644
--- a/src/messaging/imap/IMAPMessage.cpp
+++ b/src/messaging/imap/IMAPMessage.cpp
@@ -400,7 +400,7 @@ void IMAPMessage::extract(const part* p, utility::outputStream& os,
 
 	if (p != NULL)
 	{
-		const IMAPpart* currentPart = static_cast <const IMAPpart*>(p);
+		weak_ref <const IMAPpart> currentPart = static_cast <const IMAPpart*>(p);
 		std::vector <int> numbers;
 
 		numbers.push_back(currentPart->getNumber());
diff --git a/tests/utility/smartPtrTest.cpp b/tests/utility/smartPtrTest.cpp
index 44b634a6..9a7eb539 100644
--- a/tests/utility/smartPtrTest.cpp
+++ b/tests/utility/smartPtrTest.cpp
@@ -70,9 +70,6 @@ namespace
 			assert_true("6", r1 == vmime::null);
 			assert_true("7", vmime::null == r1);
 			assert_eq("8", static_cast <A*>(0), r1.get());
-
-			const A* p = r1;
-			assert_eq("9", static_cast <A*>(0), p);
 		}
 
 		void testRefCounting()
diff --git a/vmime/utility/smartPtr.hpp b/vmime/utility/smartPtr.hpp
index c20d4c06..2ef60692 100644
--- a/vmime/utility/smartPtr.hpp
+++ b/vmime/utility/smartPtr.hpp
@@ -88,7 +88,8 @@ public:
 
 
 	// Access to wrapped object
-	operator const T*() const { return m_ptr; }
+//	operator const T*() const { return m_ptr; }
+	operator const void*() const { return m_ptr; }
 
 	T& operator *() { return *m_ptr; }
 	const T& operator *() const { return *m_ptr; }
@@ -364,7 +365,8 @@ public:
 
 
 	// Access to wrapped object
-	operator const T*() const { return m_ptr; }
+//	operator const T*() const { return m_ptr; }
+	operator const void*() const { return m_ptr; }
 
 	T& operator *() { return *m_ptr; }
 	const T& operator *() const { return *m_ptr; }
@@ -375,6 +377,9 @@ public:
 	const T* const get() const { return m_ptr; }
 	T* const get() { return m_ptr; }
 
+	const bool operator !() const { return m_ptr == NULL; }
+
+
 	// dynamic_cast
 	template <class U>
 	weak_ref <U> dynamicCast() const