diff --git a/task07/main.cpp b/task07/main.cpp
index 2611933..26fc6e0 100644
--- a/task07/main.cpp
+++ b/task07/main.cpp
@@ -13,6 +13,10 @@
 #include "Eigen/Core"
 #include "Eigen/Geometry"
 
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
 /**
  * ray - sphere intersection
  * @param ray_src