diff --git a/Admin/cronjob/plain_identify b/Admin/cronjob/plain_identify
--- a/Admin/cronjob/plain_identify
+++ b/Admin/cronjob/plain_identify
@@ -1,50 +1,50 @@
 #!/bin/bash
 #
 # Plain identify job for Isabelle + AFP
 #
 
 set -e
 
 source "$HOME/.bashrc"
 
 LANG=C
 
 REPOS_DIR="$HOME/cronjob/plain_identify_repos"
 ISABELLE_REPOS_SOURCE="https://isabelle.sketis.net/repos/isabelle"
 AFP_REPOS_SOURCE="https://isabelle.sketis.net/repos/afp-devel"
 
 function setup_repos ()
 {
   local NAME="$1"
   local SOURCE="$2"
   mkdir -p "$REPOS_DIR"
   if [ ! -d "$REPOS_DIR/$NAME" ]; then
-    hg clone --noupdate -q "$SOURCE" "$REPOS_DIR/$NAME"
+    "${HG:-hg}" clone --noupdate -q "$SOURCE" "$REPOS_DIR/$NAME"
   fi
 }
 
 function identify_repos ()
 {
   local NAME="$1"
-  hg pull -R "$REPOS_DIR/$NAME" -q
-  local ID="$(hg tip -R "$REPOS_DIR/$NAME" --template "{node|short}")"
+  "${HG:-hg}" pull -R "$REPOS_DIR/$NAME" -q
+  local ID="$("${HG:-hg}" tip -R "$REPOS_DIR/$NAME" --template "{node|short}")"
   echo "$NAME version: $ID"
 }
 
 setup_repos "Isabelle" "$ISABELLE_REPOS_SOURCE"
 setup_repos "AFP" "$AFP_REPOS_SOURCE"
 
 NOW="$(date --rfc-3339=ns)"
 LOG_DIR="$HOME/cronjob/log/$(date -d "$NOW" "+%Y")"
 LOG_SECONDS="$(($(date -d "$NOW" +"%s") - $(date -d 'today 00:00:00' "+%s")))"
 LOG_NAME="plain_identify_$(date -d "$NOW" "+%Y-%m-%d").$(printf "%05d" "$LOG_SECONDS").log"
 
 mkdir -p "$LOG_DIR"
 
 {
   echo -n "isabelle_identify: "
   date -d "$NOW" "+%a %b %-d %H:%M:%S %Z %Y"
   echo
   identify_repos "Isabelle"
   identify_repos "AFP"
 } > "$LOG_DIR/$LOG_NAME"
diff --git a/Admin/cronjob/self_update b/Admin/cronjob/self_update
--- a/Admin/cronjob/self_update
+++ b/Admin/cronjob/self_update
@@ -1,17 +1,17 @@
 #!/bin/bash
 #
 # self-update of the administrative isabelle repository
 #
 # Need to copy this file manually to $HOME/cronjob in order to
 # avoid overwriting the running self_update by itself!
 
 source "$HOME/.bashrc"
 
 cd "$HOME/cronjob"
 mkdir -p run log
 
 {
-  hg -R isabelle pull "https://isabelle.sketis.net/repos/isabelle" || echo "self_update pull failed" >&2
-  hg -R isabelle update -C || echo "self_update update failed" >&2
+  "${HG:-hg}" -R isabelle pull "https://isabelle.sketis.net/repos/isabelle" || echo "self_update pull failed" >&2
+  "${HG:-hg}" -R isabelle update -C || echo "self_update update failed" >&2
   isabelle/bin/isabelle components -a 2>&1 || echo "self_update components failed" >&2
 } > run/self_update.out
diff --git a/Admin/lib/Tools/churn b/Admin/lib/Tools/churn
--- a/Admin/lib/Tools/churn
+++ b/Admin/lib/Tools/churn
@@ -1,12 +1,12 @@
 #!/usr/bin/env bash
 #
 # Author: Florian Haftmann, TU Muenchen
 #
 # DESCRIPTION: mercurial churn statistics for specified aliases file
 
 ALIAS="${1:-$ISABELLE_HOME/Admin/user-aliases}"
 shift
 
 cd "$(dirname "$ALIAS")"
 
-hg churn --aliases "$ALIAS" "$@"
+"${HG:-hg}" churn --aliases "$ALIAS" "$@"
diff --git a/Admin/lib/Tools/churn_pie b/Admin/lib/Tools/churn_pie
--- a/Admin/lib/Tools/churn_pie
+++ b/Admin/lib/Tools/churn_pie
@@ -1,14 +1,14 @@
 #!/usr/bin/env bash
 #
 # Author: Florian Haftmann, TU Muenchen
 #
 # DESCRIPTION: pie chart with Mercurial churn statistics
 
 ALIAS="${1:-$ISABELLE_HOME/Admin/user-aliases}"
 shift
 
 SCRIPT="$ISABELLE_HOME/Admin/lib/scripts/churn_pie"
 
 cd "$(dirname "$ALIAS")"
 
-hg churn --aliases "$ALIAS" | "$SCRIPT" "$@"
+"${HG:-hg}" churn --aliases "$ALIAS" | "$SCRIPT" "$@"