diff --git a/libsrc/include/CMakeLists.txt b/libsrc/include/CMakeLists.txt
index 2be510cf..be20944e 100644
--- a/libsrc/include/CMakeLists.txt
+++ b/libsrc/include/CMakeLists.txt
@@ -1,4 +1,4 @@
-install(FILES nginterface.h nginterface_v2.hpp DESTINATION ${NG_INSTALL_DIR_INCLUDE} COMPONENT netgen_devel)
+install(FILES nginterface.h nginterface_v2.hpp mydefs.hpp DESTINATION ${NG_INSTALL_DIR_INCLUDE} COMPONENT netgen_devel)
 
 install(FILES
   acisgeom.hpp csg.hpp geometry2d.hpp gprim.hpp incopengl.hpp
diff --git a/libsrc/meshing/meshclass.hpp b/libsrc/meshing/meshclass.hpp
index e996ef6d..189684d3 100644
--- a/libsrc/meshing/meshclass.hpp
+++ b/libsrc/meshing/meshclass.hpp
@@ -349,7 +349,7 @@ namespace netgen
     void SetDimension (int dim) { dimension = dim; }
 
     /// sets internal tables
-    void CalcSurfacesOfNode ();
+    DLL_HEADER void CalcSurfacesOfNode ();
 
     /// additional (temporarily) fix points 
     void FixPoints (const BitArray & fixpoints);
diff --git a/libsrc/meshing/meshtype.hpp b/libsrc/meshing/meshtype.hpp
index 10b4ca83..fd30ebac 100644
--- a/libsrc/meshing/meshtype.hpp
+++ b/libsrc/meshing/meshtype.hpp
@@ -383,13 +383,13 @@ namespace netgen
     Element2d & operator= (const Element2d &) = default;
     Element2d & operator= (Element2d &&) = default;
     ///
-    Element2d (int anp);
+    DLL_HEADER Element2d (int anp);
     ///
     DLL_HEADER Element2d (ELEMENT_TYPE type);
     ///
-    Element2d (int pi1, int pi2, int pi3);
+    DLL_HEADER Element2d (int pi1, int pi2, int pi3);
     ///
-    Element2d (int pi1, int pi2, int pi3, int pi4);
+    DLL_HEADER Element2d (int pi1, int pi2, int pi3, int pi4);
     ///
     ELEMENT_TYPE GetType () const { return typ; }
     /// 
diff --git a/libsrc/occ/occgeom.hpp b/libsrc/occ/occgeom.hpp
index 831b54ec..6229a7cc 100644
--- a/libsrc/occ/occgeom.hpp
+++ b/libsrc/occ/occgeom.hpp
@@ -244,7 +244,7 @@ namespace netgen
       }
 
 
-     virtual void Save (string filename) const;
+      DLL_HEADER virtual void Save (string filename) const;
 
 
       DLL_HEADER void BuildFMap();
@@ -275,7 +275,7 @@ namespace netgen
          return OCCSurface (TopoDS::Face(fmap(surfi)), PLANESPACE);
       }
 
-      void CalcBoundingBox ();
+      DLL_HEADER void CalcBoundingBox ();
       DLL_HEADER void BuildVisualizationMesh (double deflection);
 
       void RecursiveTopologyTree (const TopoDS_Shape & sh,
@@ -440,7 +440,7 @@ namespace netgen
    // Philippose - 31.09.2009
    // External access to the mesh generation functions within the OCC
    // subsystem (Not sure if this is the best way to implement this....!!)
-   extern int OCCGenerateMesh (OCCGeometry & occgeometry, shared_ptr<Mesh> & mesh,
+   DLL_HEADER extern int OCCGenerateMesh (OCCGeometry & occgeometry, shared_ptr<Mesh> & mesh,
 			       MeshingParameters & mparam);
 
    DLL_HEADER extern void OCCSetLocalMeshSize(OCCGeometry & geom, Mesh & mesh);
diff --git a/libsrc/occ/occmeshsurf.hpp b/libsrc/occ/occmeshsurf.hpp
index 198ade67..38172072 100644
--- a/libsrc/occ/occmeshsurf.hpp
+++ b/libsrc/occ/occmeshsurf.hpp
@@ -4,6 +4,7 @@
 #define FILE_OCCMESHSURF
 
 #include "occgeom.hpp"
+#include "mydefs.hpp"
 
 #define PARAMETERSPACE -1
 #define PLANESPACE     1
@@ -169,7 +170,7 @@ public:
 class OCCGeometry;
 
 
-class OCCRefinementSurfaces : public Refinement
+class DLL_HEADER OCCRefinementSurfaces : public Refinement
 {
   const OCCGeometry & geometry;