diff --git a/which b/which
index b6b16bf..d8f5293 100755
--- a/which
+++ b/which
@@ -7,10 +7,12 @@
 # permitted in any medium without royalty provided the copyright notice and this
 # notice are preserved.  This file is offered as-is, without any warranty.
 
+set -e
 argv0="$0"
 
 if test -z "$1"; then
 	printf "Usage: %s command...\n" "$0" 1>&2
+	exit 64 # sysexits.h(3) EX_USAGE
 fi
 
 while test -n "$1"; do
@@ -18,7 +20,7 @@ while test -n "$1"; do
 	location="$(printf "%s\n" "$out" | sed -n 's/.\+ .\+ //p')"
 
 	if [ "$location" = "found" ]; then
-		printf "%s: %s.\n" "$argv0" "$out" 1>&2
+		printf "%s: %s: Command not found.\n" "$argv0" "$1" 1>&2
 		exit 69 # sysexits(3) EX_UNAVAILABLE
 	else
 		printf "%s\n" "$location"