diff --git a/desmume/src/gtk/dTool.h b/desmume/src/gtk/dTool.h
index 24479dcd1..c27de5c70 100644
--- a/desmume/src/gtk/dTool.h
+++ b/desmume/src/gtk/dTool.h
@@ -7,7 +7,7 @@
 #include "../types.h"
 #include "../nds/interrupts.h"
 
-typedef void (*dTool_openFn)();
+typedef void (*dTool_openFn)(int id);
 typedef void (*dTool_updateFn)();
 typedef void (*dTool_closeFn)();
 
@@ -20,4 +20,6 @@ typedef struct
 	
 } dTool_t;
 
+extern void dTool_CloseCallback(int id);
+
 #endif /*__DTOOL_H__*/