diff --git a/Mixer.cpp b/Mixer.cpp
index 25c7149..3ee5c05 100644
--- a/Mixer.cpp
+++ b/Mixer.cpp
@@ -25,6 +25,8 @@ using namespace tinyxml2;
 
 #include "Mixer.h"
 
+//#define THREADED_LOADING
+
 // static semaphore to prevent multiple threads for load / save
 static std::atomic<bool> sessionThreadActive_ = false;
 static std::atomic<bool> sessionSwapRequested_ = false;
@@ -617,9 +619,13 @@ void Mixer::load(const std::string& filename)
     // create empty session
     back_session_ = new Session;
 
+#ifdef THREADED_LOADING
     // launch a thread to load the session into back_session
     // lock will be unlocked when thread ends
     std::thread (loadSession, filename, back_session_).detach();
+#else
+    loadSession (filename, back_session_);
+#endif
 }
 
 void Mixer::open(const std::string& filename)
@@ -659,9 +665,13 @@ void Mixer::import(const std::string& filename)
     // create empty session
     back_session_ = new Session;
 
+#ifdef THREADED_LOADING
     // launch a thread to load the session into back_session
     // lock will be unlocked when thread ends
     std::thread (importSession, filename, back_session_).detach();
+#else
+    importSession (filename, back_session_);
+#endif
 }
 
 void Mixer::merge(Session *session)
diff --git a/Source.cpp b/Source.cpp
index 29707d2..4786326 100644
--- a/Source.cpp
+++ b/Source.cpp
@@ -404,13 +404,14 @@ CloneSource *Source::clone()
 CloneSource::CloneSource(Source *origin) : Source(), origin_(origin)
 {
     // create surface:
-    clonesurface_ = new Surface(renderingshader_);
+    clonesurface_ = nullptr;
 }
 
 CloneSource::~CloneSource()
 {
     // delete surface
-    delete clonesurface_;
+    if (clonesurface_)
+        delete clonesurface_;
 }
 
 CloneSource *CloneSource::clone()
@@ -432,6 +433,7 @@ void CloneSource::init()
     if (origin_ && origin_->ready()) {
 
         // get the texture index from framebuffer of view, apply it to the surface
+        clonesurface_ = new Surface(renderingshader_);
         clonesurface_->setTextureIndex( origin_->texture() );
 
         // create Frame buffer matching size of session