diff --git a/usr/sbin/rear b/usr/sbin/rear
index d2cb6c070..3766e6b7d 100755
--- a/usr/sbin/rear
+++ b/usr/sbin/rear
@@ -117,6 +117,11 @@ SIMULATE=""
 VERBOSE=""
 WORKFLOW=""
 
+# Used to determine whether TMPDIR has been changed in user config
+# Can legitimately change in internal defaults, so we will set it
+# after reading them.
+saved_tmpdir
+
 # Parse options
 help_note_text="Use '$PROGRAM --help' or 'man $PROGRAM' for more information."
 if ! OPTS="$( getopt -n $PROGRAM -o "c:C:dDhsSvVr:" -l "help,version,debugscripts:" -- "$@" )" ; then
@@ -376,6 +381,9 @@ fi
 # and fd6 to get input from the user regardless where to STDIN is redirected:
 source $SHARE_DIR/lib/_input-output-functions.sh
 
+# Save the current value to detect changes.
+saved_tmpdir="${TMPDIR-}"
+
 # Keep old log file:
 test -r "$RUNTIME_LOGFILE" && mv -f "$RUNTIME_LOGFILE" "$RUNTIME_LOGFILE".old 2>/dev/null
 
@@ -446,6 +454,14 @@ for config in site local rescue ; do
         test "$( tr -d -c '\r' < $CONFIG_DIR/$config.conf )" && Error "Carriage return character in $CONFIG_DIR/$config.conf (perhaps DOS or Mac format)"
         Source "$CONFIG_DIR/$config.conf" || true
     fi
+    if [ "$config" == local ] ; then
+        # changing TMPDIR in rescue.conf is expected for now, see
+        # rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh,
+        # so perform the check after reading local.conf but before rescue.conf
+        if [ "$saved_tmpdir" != "${TMPDIR-}" ] ; then
+            LogPrintError "Warning: Setting TMPDIR in a configuration file is deprecated. To specify a working area directory prefix, export TMPDIR before executing '$PROGRAM'"
+        fi
+    fi
 done
 # Finally source additional configuration files if specified on the command line:
 if test "$CONFIG_APPEND_FILES" ; then
diff --git a/usr/share/rear/conf/default.conf b/usr/share/rear/conf/default.conf
index d5fe6dcc4..4e67e38c9 100644
--- a/usr/share/rear/conf/default.conf
+++ b/usr/share/rear/conf/default.conf
@@ -50,12 +50,9 @@
 # which usually results /tmp/rear.XXXXXXXXXXXXXXX or $TMPDIR/rear.XXXXXXXXXXXXXXX
 # the latter when the canonical Linux/Unix environment variable TMPDIR
 # is set in the environment where /usr/sbin/rear is called.
-# To have a specific working area directory prefix for Relax-and-Recover
-# specify in /etc/rear/local.conf something like
-#
+# To have a specific working area directory prefix for Relax-and-Recover call
 #   export TMPDIR="/prefix/for/rear/working/directory"
-#
-# where /prefix/for/rear/working/directory must already exist.
+# before calling 'rear' (/prefix/for/rear/working/directory must already exist).
 # This is useful for example when there is not sufficient free space
 # in /var/tmp or $TMPDIR for the ISO image or even the backup archive.
 # TMPDIR cannot be set to a default value here unconditionally but only
diff --git a/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh b/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh
new file mode 100644
index 000000000..84d0cabb2
--- /dev/null
+++ b/usr/share/rear/rescue/GNU/Linux/600_unset_TMPDIR_in_rescue_conf.sh
@@ -0,0 +1,8 @@
+cat - <<EOF >> "$ROOTFS_DIR/etc/rear/rescue.conf"
+# TMPDIR variable may be defined in local.conf file as prefix dir for mktemp command
+# e.g. by defining TMPDIR=/var we would get our BUILD_DIR=/var/tmp/rear.XXXXXXXXXXXX
+# However, in rescue we want our BUILD_DIR=/tmp/rear.XXXXXXX as we are not sure that
+# the user defined TMPDIR would exist in our rescue image
+# by 'unset TMPDIR' we achieve above goal (as rescue.conf is read after local.conf)!
+unset TMPDIR
+EOF