1 files changed, 6 insertions, 0 deletions
diff --git a/src/intersect.h b/src/intersect.h
index 92bcf0c..e6566f3 100644
--- a/src/intersect.h
+++ b/src/intersect.h
@@ -1,4 +1,8 @@
 //-*-c-*-
+
+#ifndef __INTERSECT_H__
+#define __INTERSECT_H__
+
 #include <math_constants.h>
 
 #include "linalg.h"
@@ -145,3 +149,5 @@ __device__ bool intersect_box(const float3 &origin, const float3 &direction, con
 
 	return true;
 }
+
+#endif