diff -purN a/source/blender/render/intern/raytrace/rayobject_rtbuild.cpp b/source/blender/render/intern/raytrace/rayobject_rtbuild.cpp
--- a/source/blender/render/intern/raytrace/rayobject_rtbuild.cpp	2016-09-28 10:26:55.000000000 +0100
+++ b/source/blender/render/intern/raytrace/rayobject_rtbuild.cpp	2016-10-04 11:13:46.489404123 +0100
@@ -34,6 +34,7 @@
 #include <math.h>
 #include <stdlib.h>
 #include <algorithm>
+#include <cmath>
 
 #include "rayobject_rtbuild.h"