diff --git a/src/defines.h b/src/defines.h
index 2c634398..a2fd9ec9 100644
--- a/src/defines.h
+++ b/src/defines.h
@@ -42,6 +42,9 @@
 #ifndef PI
 #define PI 3.141592654 /* mathematical constant                */
 #endif
+#ifndef M_PI
+#define M_PI 3.14159265358979323846f
+#endif
 #define TWO_PI 6.283185307 /* mathematical constant                */
 #define MAX_STR 2048       /* maximum string size                  */