diff --git a/rtengine/dfmanager.cc b/rtengine/dfmanager.cc
index 5f1035a8e..7de712fb5 100644
--- a/rtengine/dfmanager.cc
+++ b/rtengine/dfmanager.cc
@@ -270,8 +270,11 @@ void dfInfo::updateBadPixelList( RawImage *df )
 
 // ************************* class DFManager *********************************
 
-void DFManager::init( Glib::ustring pathname )
+void DFManager::init(const Glib::ustring& pathname)
 {
+    if (pathname.empty()) {
+        return;
+    }
     std::vector<Glib::ustring> names;
 
     auto dir = Gio::File::create_for_path (pathname);
diff --git a/rtengine/dfmanager.h b/rtengine/dfmanager.h
index 62379187b..2e55c3c22 100644
--- a/rtengine/dfmanager.h
+++ b/rtengine/dfmanager.h
@@ -78,7 +78,7 @@ protected:
 class DFManager
 {
 public:
-    void init( Glib::ustring pathname );
+    void init(const Glib::ustring &pathname);
     Glib::ustring getPathname()
     {
         return currentPath;
diff --git a/rtengine/ffmanager.cc b/rtengine/ffmanager.cc
index 6b0302d1e..6e4977076 100644
--- a/rtengine/ffmanager.cc
+++ b/rtengine/ffmanager.cc
@@ -231,8 +231,11 @@ void ffInfo::updateRawImage()
 
 // ************************* class FFManager *********************************
 
-void FFManager::init( Glib::ustring pathname )
+void FFManager::init(const Glib::ustring& pathname)
 {
+    if (pathname.empty()) {
+        return;
+    }
     std::vector<Glib::ustring> names;
 
     auto dir = Gio::File::create_for_path (pathname);
diff --git a/rtengine/ffmanager.h b/rtengine/ffmanager.h
index 7022d1641..9068216ef 100644
--- a/rtengine/ffmanager.h
+++ b/rtengine/ffmanager.h
@@ -75,7 +75,7 @@ protected:
 class FFManager
 {
 public:
-    void init( Glib::ustring pathname );
+    void init(const Glib::ustring &pathname);
     Glib::ustring getPathname()
     {
         return currentPath;
diff --git a/rtgui/filmsimulation.cc b/rtgui/filmsimulation.cc
index aee06f310..734b46c34 100644
--- a/rtgui/filmsimulation.cc
+++ b/rtgui/filmsimulation.cc
@@ -300,7 +300,7 @@ ClutComboBox::ClutModel::ClutModel(const Glib::ustring &path)
 {
     m_model = Gtk::TreeStore::create (m_columns);
     //set_model (m_model);
-    count = parseDir(path);
+    count = path.empty() ? 0 : parseDir(path);
 }
 
 int ClutComboBox::ClutModel::parseDir(const Glib::ustring& path)