diff --git a/intern/cycles/util/util_boundbox.h b/intern/cycles/util/util_boundbox.h
index 24ea3655576..0114a9a26a5 100644
--- a/intern/cycles/util/util_boundbox.h
+++ b/intern/cycles/util/util_boundbox.h
@@ -19,12 +19,15 @@
 #ifndef __UTIL_BOUNDBOX_H__
 #define __UTIL_BOUNDBOX_H__
 
+#include <math.h>
 #include <float.h>
-#include <cmath>
 
+#include "util_math.h"
 #include "util_transform.h"
 #include "util_types.h"
 
+using namespace std;
+
 CCL_NAMESPACE_BEGIN
 
 class BoundBox
@@ -73,8 +76,8 @@ public:
 	bool valid(void) const
 	{
 		return (min.x <= max.x) && (min.y <= max.y) && (min.z <= max.z) &&
-		       !(std::isnan(min.x) || std::isnan(min.y) || std::isnan(min.z)) &&
-		       !(std::isnan(max.x) || std::isnan(max.y) || std::isnan(max.z));
+		       !(isnan(min.x) || isnan(min.y) || isnan(min.z)) &&
+		       !(isnan(max.x) || isnan(max.y) || isnan(max.z));
 	}
 
 	BoundBox transformed(const Transform *tfm)
diff --git a/intern/cycles/util/util_math.h b/intern/cycles/util/util_math.h
index 2f9e00dbfcb..7c56f0fbb12 100644
--- a/intern/cycles/util/util_math.h
+++ b/intern/cycles/util/util_math.h
@@ -63,6 +63,7 @@ CCL_NAMESPACE_BEGIN
 #if(!defined(FREE_WINDOWS))
 #define copysignf(x, y) ((float)_copysign(x, y))
 #define hypotf(x, y) _hypotf(x, y)
+#define isnan(x) _isnan(x)
 #endif
 
 #endif