diff --git a/libsrc/general/myadt.hpp b/libsrc/general/myadt.hpp
index aac10338..493bc7b4 100644
--- a/libsrc/general/myadt.hpp
+++ b/libsrc/general/myadt.hpp
@@ -17,7 +17,7 @@
 #include "../include/mydefs.hpp"
 
 
-#include "../core/ngcore.hpp"
+#include <core/ngcore.hpp>
 namespace netgen
 {
   using namespace ngcore;
diff --git a/libsrc/include/nginterface.h b/libsrc/include/nginterface.h
index 0a0a276f..bbdd267c 100644
--- a/libsrc/include/nginterface.h
+++ b/libsrc/include/nginterface.h
@@ -11,7 +11,7 @@
 /* Date:   20. Nov. 99                                                    */
 /**************************************************************************/
 
-#include "../core/ngcore.hpp"
+#include <core/ngcore.hpp>
 
 /*
   Application program interface to Netgen
diff --git a/libsrc/include/nginterface_v2.hpp b/libsrc/include/nginterface_v2.hpp
index b760a9e7..6e06fc82 100644
--- a/libsrc/include/nginterface_v2.hpp
+++ b/libsrc/include/nginterface_v2.hpp
@@ -8,7 +8,7 @@
 /* Date:   May  09                                                        */
 /**************************************************************************/
 
-#include "../core/ngcore.hpp"
+#include <core/ngcore.hpp>
 
 /*
   C++ interface to Netgen