diff --git a/src/math/mv4.h b/src/math/mv4.h
index a74d9b3..b3bcfe4 100644
--- a/src/math/mv4.h
+++ b/src/math/mv4.h
@@ -1,4 +1,9 @@
+#ifndef MV4_H
+#define MV4_H
+
 #include "mat4.h"
 #include "vec4.h"
 
-Vec4f_t mat4f_mul_vec4f(const Mat4f_t mat, Vec4f_t v);
\ No newline at end of file
+Vec4f_t mat4f_mul_vec4f(const Mat4f_t mat, Vec4f_t v);
+
+#endif  // MATRIX4_H