diff --git a/src/g_undo.c b/src/g_undo.c
index 6f274a894f9c21a4c0fc723ab584bc3a420b369b..9b9d5226e9a5898f736554df086a47537f9955c4 100644
--- a/src/g_undo.c
+++ b/src/g_undo.c
@@ -86,6 +86,7 @@ void canvas_undo_undo(t_canvas *x)
 			sys_vgui("pdtk_undomenu .x%lx %s %s\n", x, undo_action, redo_action);
 			sys_vgui("pdtk_canvas_getscroll .x%lx.c\n", x);
 		}
+		canvas_dirty(x, 1);
 	}
     canvas_resume_dsp(dspwas);
 }
@@ -125,6 +126,7 @@ void canvas_undo_redo(t_canvas *x)
 			sys_vgui("pdtk_undomenu .x%lx %s %s\n", x, undo_action, redo_action);
 			sys_vgui("pdtk_canvas_getscroll .x%lx.c\n", x);
 		}
+		canvas_dirty(x, 1);
 	}
     canvas_resume_dsp(dspwas);
 }