diff --git a/fpdfsdk/cpdfsdk_annot.h b/fpdfsdk/cpdfsdk_annot.h
index 22e5515..b476014 100644
--- a/fpdfsdk/cpdfsdk_annot.h
+++ b/fpdfsdk/cpdfsdk_annot.h
@@ -32,6 +32,10 @@
   virtual CFX_FloatRect GetRect() const = 0;
   virtual bool DoHitTest(const CFX_PointF& point) = 0;
   virtual CFX_FloatRect GetViewBBox() = 0;
+  virtual bool CanUndo() = 0;
+  virtual bool CanRedo() = 0;
+  virtual bool Undo() = 0;
+  virtual bool Redo() = 0;
 
   // Three cases: PDF page only, XFA page only, or XFA page backed by PDF page.
   IPDF_Page* GetPage();     // Returns XFA Page if possible, else PDF page.