diff --git a/scripts/purge-stale-projects.sh b/scripts/purge-stale-projects.sh
index 016a6310..44f880bd 100644
--- a/scripts/purge-stale-projects.sh
+++ b/scripts/purge-stale-projects.sh
@@ -45,6 +45,13 @@ ssh=ssh
 [ "$CVS_RSH" ] && ssh="$CVS_RSH"
 [ "$GIT_SSH" ] && ssh="$GIT_SSH"
 [ "$JANWARE_USER" ] || JANWARE_USER=`whoami`
+ssh=`which $ssh`
+
+[ -x "$ssh" ] || {
+	echo "SSH executable \"$ssh\" not found"
+	exit 1
+}
+
 ssh="$ssh -l $JANWARE_USER"
 local_cvs_proj=`ls -d */CVS 2>/dev/null | sed 's%/[^/]*%%'`
 local_git_proj=`ls -d */.git 2>/dev/null | sed 's%/[^/]*%%'`