diff --git a/CMakeLists.txt b/CMakeLists.txt
index 71dcb77..676643a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,18 @@ message(WARNING "Version to build: ${GRIVE_VERSION}")
 # common compile options
 add_definitions( -DVERSION="${GRIVE_VERSION}" )
 add_definitions( -D_FILE_OFFSET_BITS=64 -std=c++0x )
+if ( APPLE )
+	add_definitions( -Doff64_t=off_t )
+endif ( APPLE )
+
+find_program(
+	HAVE_SYSTEMD systemd
+	PATHS /lib/systemd /usr/lib/systemd
+	NO_DEFAULT_PATH
+)
+if ( HAVE_SYSTEMD )
+	add_subdirectory( systemd )
+endif( HAVE_SYSTEMD )
 
-add_subdirectory( systemd )
 add_subdirectory( libgrive )
 add_subdirectory( grive )
diff --git a/libgrive/src/base/Feed.cc b/libgrive/src/base/Feed.cc
index 0ea834d..0a4f51b 100644
--- a/libgrive/src/base/Feed.cc
+++ b/libgrive/src/base/Feed.cc
@@ -30,6 +30,10 @@ Feed::Feed( const std::string &url ):
 {
 }
 
+Feed::~Feed()
+{
+}
+
 Feed::iterator Feed::begin() const
 {
 	return m_entries.begin() ;
diff --git a/libgrive/src/base/Feed.hh b/libgrive/src/base/Feed.hh
index d43c68c..c12f507 100644
--- a/libgrive/src/base/Feed.hh
+++ b/libgrive/src/base/Feed.hh
@@ -41,6 +41,7 @@ public :
 public :
 	Feed( const std::string& url );
 	virtual bool GetNext( http::Agent *http ) = 0 ;
+	virtual ~Feed() = 0 ;
 	iterator begin() const ;
 	iterator end() const ;
 
diff --git a/libgrive/src/drive2/Feed2.cc b/libgrive/src/drive2/Feed2.cc
index 8f3d234..037df37 100644
--- a/libgrive/src/drive2/Feed2.cc
+++ b/libgrive/src/drive2/Feed2.cc
@@ -36,6 +36,10 @@ Feed2::Feed2( const std::string& url ):
 {
 }
 
+Feed2::~Feed2()
+{
+}
+
 bool Feed2::GetNext( http::Agent *http )
 {
 	if ( m_next.empty() )
diff --git a/libgrive/src/drive2/Feed2.hh b/libgrive/src/drive2/Feed2.hh
index 4de411e..c5643f6 100644
--- a/libgrive/src/drive2/Feed2.hh
+++ b/libgrive/src/drive2/Feed2.hh
@@ -31,6 +31,7 @@ class Feed2: public Feed
 {
 public :
 	Feed2( const std::string& url ) ;
+	~Feed2() ;
 	bool GetNext( http::Agent *http ) ;
 } ;