diff --git a/workbench/libs/amigaguide/amigaguide.conf b/workbench/libs/amigaguide/amigaguide.conf
index 8f38fa27bf..47e48bcfea 100644
--- a/workbench/libs/amigaguide/amigaguide.conf
+++ b/workbench/libs/amigaguide/amigaguide.conf
@@ -1,6 +1,5 @@
 ##begin config
 basename AmigaGuide
-libbasetype struct AmigaGuideBase_intern
 version 41.0
 date 15.12.2003
 libcall registermacro
diff --git a/workbench/libs/amigaguide/amigaguide_intern.h b/workbench/libs/amigaguide/amigaguide_intern.h
index 21c7887a61..33f6f97e98 100644
--- a/workbench/libs/amigaguide/amigaguide_intern.h
+++ b/workbench/libs/amigaguide/amigaguide_intern.h
@@ -15,9 +15,6 @@
 #ifndef EXEC_LIBRARIES_H
 #   include <exec/libraries.h>
 #endif
-#ifndef LIBCORE_BASE_H
-#   include <libcore/base.h>
-#endif
 
 #ifndef LIBRARIES_AMIGAGUIDE_H
 #   include <libraries/amigaguide.h>
@@ -31,13 +28,12 @@
 
 
 /* Predeclaration */
-LIBBASETYPE;
 
 
 /**************
 **  Defines  **
 **************/
-#define SysBase (((struct LibHeader *) AmigaGuideBase)->lh_SysBase)
+#define SysBase GM_SYSBASE_FIELD(((LIBBASETYPEPTR)AmigaGuideBase))
 
 
 /*****************
@@ -49,10 +45,4 @@ LIBBASETYPE;
 **  Library stuff  **
 ********************/
 
-
-LIBBASETYPE
-{
-    struct LibHeader lh;
-};
-
 #endif /* AMIGAGUIDE_INTERN_H */