diff --git a/usr.bin/hexdump/parse.c b/usr.bin/hexdump/parse.c
index d11071b8c3a3..bd96462776a2 100644
--- a/usr.bin/hexdump/parse.c
+++ b/usr.bin/hexdump/parse.c
@@ -151,7 +151,7 @@ add(fmt)
 	}
 }
 
-static char spec[] = ".#-+ 0123456789";
+static const char *spec = ".#-+ 0123456789";
 
 int
 size(fs)