diff --git a/app/startup.sh b/app/startup.sh
index 95ff947..cd6a9a7 100755
--- a/app/startup.sh
+++ b/app/startup.sh
@@ -5,8 +5,10 @@ while ! pg_isready -h $DB_HOST -U $DB_USER; do
 	sleep 3
 done
 
-addgroup -g $OWNER_GID app
-adduser -D -h /var/www/html -G app -u $OWNER_UID app
+if ! id app; then
+	addgroup -g $OWNER_GID app
+	adduser -D -h /var/www/html -G app -u $OWNER_UID app
+fi
 
 DST_DIR=/var/www/html/tt-rss
 SRC_REPO=https://git.tt-rss.org/fox/tt-rss.git
diff --git a/app/updater.sh b/app/updater.sh
index f81d83e..480a5d1 100755
--- a/app/updater.sh
+++ b/app/updater.sh
@@ -3,8 +3,10 @@
 # wait for the app container to delete .app_is_ready and perform rsync, etc.
 sleep 30
 
-addgroup -g $OWNER_GID app
-adduser -D -h /var/www/html -G app -u $OWNER_UID app
+if ! id app; then
+	addgroup -g $OWNER_GID app
+	adduser -D -h /var/www/html -G app -u $OWNER_UID app
+fi
 
 while ! pg_isready -h $DB_HOST -U $DB_USER; do
 	echo waiting until $DB_HOST is ready...