diff --git a/source/dft/functionals.h b/source/dft/functionals.h
index fde49ba..f7a61fc 100644
--- a/source/dft/functionals.h
+++ b/source/dft/functionals.h
@@ -59,6 +59,14 @@
 #define EXTERN_C
 #endif
 
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+#ifndef M_SQRT2
+#define M_SQRT2        1.41421356237309504880
+#endif
+
 typedef ergo_real real;
 
 #if defined(FUNC_PRECISION) && FUNC_PRECISION == 1