diff --git a/DDG4/plugins/Geant4SensDet.cpp b/DDG4/plugins/Geant4SensDet.cpp
index 36669acc4da3253e798510f0d23e7e346ff65ada..5061a4388e2d0e6cbc432422dce7d1093e7e89ec 100644
--- a/DDG4/plugins/Geant4SensDet.cpp
+++ b/DDG4/plugins/Geant4SensDet.cpp
@@ -81,7 +81,7 @@ namespace DD4hep {
           Geant4Action(0,nam), Geant4ActionSD(nam), Base()
       {
         Geant4Kernel& master = Geant4Kernel::instance(lcdd);
-        Geant4Kernel& kernel = master.worker(::pthread_self());
+        Geant4Kernel& kernel = master.worker(Geant4Kernel::thread_self());
         m_sensitive   = lcdd.sensitiveDetector(nam);
         m_context     = kernel.workerContext();
         m_outputLevel = kernel.getOutputLevel(nam);
diff --git a/DDRec/src/Surface.cpp b/DDRec/src/Surface.cpp
index 614e9f596ad0ad643318595a18baef55fd856c79..555b8822dee9ca9c705f9453df24611ae812996c 100644
--- a/DDRec/src/Surface.cpp
+++ b/DDRec/src/Surface.cpp
@@ -607,7 +607,7 @@ namespace DD4hep {
 	
         MaterialManager matMgr ;
         
-	Vector3D p = _o - outerThickness() * _n  ;
+	Vector3D p = _o + outerThickness() * _n  ;
 
         const MaterialVec& materials = matMgr.materialsBetween( _o , p  ) ;