diff --git a/sh.h b/sh.h
index c4128bf..1cec417 100644
--- a/sh.h
+++ b/sh.h
@@ -182,9 +182,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.865 2018/08/10 02:53:37 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.866 2018/10/20 18:45:58 tg Exp $");
 #endif
-#define MKSH_VERSION "R56 2018/07/15"
+#define MKSH_VERSION "R56 2018/10/20"
 
 /* arithmetic types: C implementation */
 #if !HAVE_CAN_INTTYPES
@@ -2637,7 +2637,7 @@ const char *wdscan(const char *, int);
 #define WDS_TPUTS	BIT(0)		/* tputS (dumpwdvar) mode */
 char *wdstrip(const char *, int);
 void tfree(struct op *, Area *);
-void dumpchar(struct shf *, int);
+void dumpchar(struct shf *, unsigned char);
 void dumptree(struct shf *, struct op *);
 void dumpwdvar(struct shf *, const char *);
 void dumpioact(struct shf *shf, struct op *t);
diff --git a/tree.c b/tree.c
index 61a2e06..335e3fb 100644
--- a/tree.c
+++ b/tree.c
@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/tree.c,v 1.96 2018/08/10 02:53:39 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/tree.c,v 1.97 2018/10/20 18:46:00 tg Exp $");
 
 #define INDENT	8
 
@@ -821,7 +821,7 @@ vistree(char *dst, size_t sz, struct op *t)
 
 #ifdef DEBUG
 void
-dumpchar(struct shf *shf, int c)
+dumpchar(struct shf *shf, unsigned char c)
 {
 	if (ksh_isctrl(c)) {
 		/* C0 or C1 control character or DEL */