diff --git a/libsrc/gprim/geom2d.cpp b/libsrc/gprim/geom2d.cpp
index 7d051359..f50131aa 100644
--- a/libsrc/gprim/geom2d.cpp
+++ b/libsrc/gprim/geom2d.cpp
@@ -3,10 +3,6 @@
 #include <myadt.hpp>
 #include <gprim.hpp>
 
-#ifndef M_PI
-#define M_PI        3.14159265358979323846
-#endif
-
 namespace netgen
 {
 
diff --git a/libsrc/gprim/geomfuncs.cpp b/libsrc/gprim/geomfuncs.cpp
index b2ac8382..6608c072 100644
--- a/libsrc/gprim/geomfuncs.cpp
+++ b/libsrc/gprim/geomfuncs.cpp
@@ -83,7 +83,7 @@ double Det (const Mat<3,3> & m)
 
 void EigenValues (const Mat<3,3> & m, Vec<3> & ev)
 {
-  const double pi = 3.141592;
+  const double pi = M_PI;
   double a, b, c, d;
   double p, q;
   double arg;
diff --git a/libsrc/occ/Partition_Loop2d.cxx b/libsrc/occ/Partition_Loop2d.cxx
index 22740a58..1c3d7957 100644
--- a/libsrc/occ/Partition_Loop2d.cxx
+++ b/libsrc/occ/Partition_Loop2d.cxx
@@ -52,8 +52,6 @@
 #include <gp_Pnt.hxx>
 #include <gp_Pnt2d.hxx>
 
-#define PI 3.14159265358979323846
-
 //=======================================================================
 //function : Partition_Loop2d
 //purpose  :