diff --git a/netboot.h b/netboot.h
index 2cdb421..6417373 100644
--- a/netboot.h
+++ b/netboot.h
@@ -5,5 +5,5 @@ extern BOOLEAN findNetboot(EFI_HANDLE image_handle);
 
 extern EFI_STATUS parseNetbootinfo(EFI_HANDLE image_handle);
 
-extern EFI_STATUS FetchNetbootimage(EFI_HANDLE image_handle, VOID **buffer, UINTN *bufsiz);
+extern EFI_STATUS FetchNetbootimage(EFI_HANDLE image_handle, VOID **buffer, UINT64 *bufsiz);
 #endif