1 files changed, 6 insertions, 1 deletions
diff --git a/src/document-undo.h b/src/document-undo.h
index 087e12b5a..38e575a34 100644
--- a/src/document-undo.h
+++ b/src/document-undo.h
@@ -1,13 +1,18 @@
 #ifndef SEEN_SP_DOCUMENT_UNDO_H
 #define SEEN_SP_DOCUMENT_UNDO_H
 
+namespace Glib {
+    class ustring;
+}
+
 typedef struct _GObject GObject;
 
 class SPDesktop;
+class SPDocument;
 
 namespace Inkscape {
 
-class Application;
+struct Application;
 
 class DocumentUndo
 {