diff --git a/src/engine/camera_interp_skip.c b/src/engine/camera_interp_skip.c
index 2a458a5a..0d2f6569 100644
--- a/src/engine/camera_interp_skip.c
+++ b/src/engine/camera_interp_skip.c
@@ -1,3 +1,6 @@
+#ifndef CAMERA_INTERP_SKIP_C
+#define CAMERA_INTERP_SKIP_C
+
 #include "global.h"
 
 #define SQXYZ(vec) ((vec.x) * (vec.x) + (vec.y) * (vec.y) + (vec.z) * (vec.z))
@@ -105,4 +108,6 @@ bool should_interpolate_perspective(Vec3f* eye, Vec3f* at) {
     }
 
     return true;
-}
\ No newline at end of file
+}
+
+#endif