diff --git a/src/proto.h b/src/proto.h
index 01d464e5..7b085dff 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -751,7 +751,6 @@ void new_magicline(void);
 void remove_magicline(void);
 void mark_order(const filestruct **top, size_t *top_x, const filestruct
 	**bot, size_t *bot_x, bool *right_side_up);
-void discard_until(undo *thisone);
 void add_undo(undo_type action);
 void update_undo(undo_type action);
 #endif