diff --git a/usr.bin/hexdump/hexdump.h b/usr.bin/hexdump/hexdump.h
index be85bd9ca4c3..e34d3a011300 100644
--- a/usr.bin/hexdump/hexdump.h
+++ b/usr.bin/hexdump/hexdump.h
@@ -82,9 +82,9 @@ enum _vflag { ALL, DUP, FIRST, WAIT };	/* -v values */
 extern enum _vflag vflag;
 
 void	 add(const char *);
-void	 addfile(char *);
-void	 badcnt(char *);
-void	 badconv(char *);
+void	 addfile(const char *);
+void	 badcnt(const char *);
+void	 badconv(const char *);
 void	 badfmt(const char *);
 void	 badsfmt(void);
 void	 bpad(PR *);
diff --git a/usr.bin/hexdump/parse.c b/usr.bin/hexdump/parse.c
index 10db904dc0e6..1e0612028f86 100644
--- a/usr.bin/hexdump/parse.c
+++ b/usr.bin/hexdump/parse.c
@@ -48,7 +48,7 @@ __FBSDID("$FreeBSD$");
 FU *endfu;					/* format at end-of-data */
 
 void
-addfile(char *name)
+addfile(const char *name)
 {
 	unsigned char *p;
 	FILE *fp;
@@ -491,7 +491,7 @@ escape(char *p1)
 }
 
 void
-badcnt(char *s)
+badcnt(const char *s)
 {
 	errx(1, "%s: bad byte count", s);
 }
@@ -509,7 +509,7 @@ badfmt(const char *fmt)
 }
 
 void
-badconv(char *ch)
+badconv(const char *ch)
 {
 	errx(1, "%%%s: bad conversion character", ch);
 }