diff --git a/common.h b/common.h
index 6399bbe..cca606d 100644
--- a/common.h
+++ b/common.h
@@ -1,5 +1,7 @@
-#pragma once
+#ifndef COMMONH
+    typedef unsigned char byte; //8bit (byte) variable type
+    typedef unsigned short word; //16bit (2byte) variable type
+    typedef enum {false, true} bool;
+#endif
 
-typedef unsigned char byte; //8bit (byte) variable type
-typedef unsigned short word; //16bit (2byte) variable type
-typedef enum {false, true} bool;
\ No newline at end of file
+#define COMMONH
\ No newline at end of file