1 files changed, 5 insertions, 0 deletions
diff --git a/openscad.h b/openscad.h
index 133a99f..3693101 100644
--- a/openscad.h
+++ b/openscad.h
@@ -44,6 +44,11 @@
 #include <fstream>
 #include <iostream>
 
+// for win32 and maybe others..
+#ifndef M_PI
+#  define M_PI 3.14159265358979323846
+#endif
+
 class Value;
 class Expression;