diff --git a/putty.h b/putty.h
index edb5eb4c..7b7486a5 100644
--- a/putty.h
+++ b/putty.h
@@ -2399,12 +2399,6 @@ char const *conf_dest(Conf *conf);
  */
 void prepare_session(Conf *conf);
 
-/*
- * Exports from sercfg.c.
- */
-void ser_setup_config_box(struct controlbox *b, bool midsession,
-                          int parity_mask, int flow_mask);
-
 /*
  * Exports from version.c.
  */