diff --git a/protonkey b/protonkey
index 6916bd4..ac13b06 100755
--- a/protonkey
+++ b/protonkey
@@ -1,23 +1,26 @@
 #!/bin/sh
 
-# Copyright (c) 2022 Emma Tebibyte
+# Copyright (c) 2022–2023 Emma Tebibyte <emma@tebibyte.media>
 # SPDX-License-Identifier: AGPL-3.0-or-later
 #
-# Protonkey is free software: you can redistribute it and/or modify it
-# under the terms of the GNU Affero General Public License as published by the
-# Free Software Foundation, either version 3 of the License, or (at your
-# option) any later version.
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
 # 
-# Protonkey is distributed in the hope that it will be useful, but WITHOUT
+# This program is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 # FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
 # details.
 #
-# You should have received a copy of the GNU Affero General Public License
-# along with this program. If not, see https://www.gnu.org/licenses/.
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see https://www.gnu.org/licenses/.
+
+
+argv0="$0"
 
 if test -z "$1"; then
-  printf "Usage: %s [ProtonMail address]\n" "$0" 1>&2
+  printf "Usage: %s [ProtonMail address...]\n" "$argv0" 1>&2
   exit 64 # syexits(3) EX_USAGE
 fi
 
@@ -31,13 +34,15 @@ do
   fi
 done
 
-URL="https://api.protonmail.ch/pks/lookup?op=get&search=$1"
-RESPONSE="$(curl -s "$URL")"
+while test -n "$1"; do
+  URL="https://api.protonmail.ch/pks/lookup?op=get&search=$1"
+  RESPONSE="$(curl -s "$URL")"
 
-if [ "$RESPONSE" = 'No key found' ]; then
-  printf "%s\n" "$RESPONSE" 1>&2
-  exit 76 # sysexits(3) EX_PROTOCOL
-else
-  printf "%s\n" "$RESPONSE"
-  exit 0
-fi
+  if [ "$RESPONSE" = 'No key found' ]; then
+    printf "%s: %s: %s\n" "$argv0" "$1" "$RESPONSE" 1>&2
+    exit 76 # sysexits(3) EX_PROTOCOL
+  else
+    printf "%s\n" "$RESPONSE"
+  fi
+shift
+done