diff --git a/types.h b/types.h
index c4c43e6..cb972d9 100644
--- a/types.h
+++ b/types.h
@@ -1,3 +1,5 @@
+#ifndef TYPES_H
+#define TYPES_H
 typedef unsigned char u8;
 typedef unsigned short u16;
 typedef unsigned long u32;
@@ -8,4 +10,4 @@ typedef signed short s16;
 typedef signed long s32;
 typedef signed long long s64;
 
-
+#endif