diff --git a/contrib/ssh-copy-id b/contrib/ssh-copy-id
index bef5c95d9..b83b83619 100644
--- a/contrib/ssh-copy-id
+++ b/contrib/ssh-copy-id
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-# Copyright (c) 1999-2013 Philip Hands <phil@hands.com>
+# Copyright (c) 1999-2016 Philip Hands <phil@hands.com>
 #               2013 Martin Kletzander <mkletzan@redhat.com>
 #               2010 Adeodato =?iso-8859-1?Q?Sim=F3?= <asp16@alu.ua.es>
 #               2010 Eric Moret <eric.moret@gmail.com>
@@ -56,7 +56,8 @@ then
   fi
 fi
 
-DEFAULT_PUB_ID_FILE="$HOME/$(cd "$HOME" ; ls -t .ssh/id*.pub 2>/dev/null | grep -v -- '-cert.pub$' | head -n 1)"
+most_recent_id="$(cd "$HOME" ; ls -t .ssh/id*.pub 2>/dev/null | grep -v -- '-cert.pub$' | head -n 1)"
+DEFAULT_PUB_ID_FILE="${most_recent_id:+$HOME/}$most_recent_id"
 
 usage () {
   printf 'Usage: %s [-h|-?|-f|-n] [-i [identity_file]] [-p port] [[-o <ssh -o options>] ...] [user@]hostname\n' "$0" >&2
@@ -74,6 +75,11 @@ quote() {
 use_id_file() {
   local L_ID_FILE="$1"
 
+  if [ -z "$L_ID_FILE" ] ; then
+    printf "%s: ERROR: no ID file found\n" "$0"
+    exit 1
+  fi
+
   if expr "$L_ID_FILE" : ".*\.pub$" >/dev/null ; then
     PUB_ID_FILE="$L_ID_FILE"
   else
@@ -287,9 +293,10 @@ case "$REMOTE_VERSION" in
   *)
     # Assuming that the remote host treats ~/.ssh/authorized_keys as one might expect
     populate_new_ids 0
-    # in ssh below - to defend against quirky remote shells: use 'exec sh -c' to get POSIX; 'cd' to be at $HOME; and all on one line, because tcsh.
+    # in ssh below - to defend against quirky remote shells: use 'exec sh -c' to get POSIX;
+    #     'cd' to be at $HOME; add a newline if it's missing; and all on one line, because tcsh.
     [ "$DRY_RUN" ] || printf '%s\n' "$NEW_IDS" | \
-      ssh "$@" "exec sh -c 'cd ; umask 077 ; mkdir -p .ssh && cat >> .ssh/authorized_keys || exit 1 ; if type restorecon >/dev/null 2>&1 ; then restorecon -F .ssh .ssh/authorized_keys ; fi'" \
+      ssh "$@" "exec sh -c 'cd ; umask 077 ; mkdir -p .ssh && { [ -z "'`tail -1c .ssh/authorized_keys 2>/dev/null`'" ] || echo >> .ssh/authorized_keys ; } && cat >> .ssh/authorized_keys || exit 1 ; if type restorecon >/dev/null 2>&1 ; then restorecon -F .ssh .ssh/authorized_keys ; fi'" \
       || exit 1
     ADDED=$(printf '%s\n' "$NEW_IDS" | wc -l)
     ;;