diff --git a/docker/images/files/nginx-entrypoint.sh b/docker/images/files/nginx-entrypoint.sh
index 7180b07603..1c6621fba3 100644
--- a/docker/images/files/nginx-entrypoint.sh
+++ b/docker/images/files/nginx-entrypoint.sh
@@ -15,16 +15,14 @@ fi
 
 update_flags() {
   if [ -n "$PENPOT_FLAGS" ]; then
-    sed -i \
+    echo "$(sed \
       -e "s|^//var penpotFlags = .*;|var penpotFlags = \"$PENPOT_FLAGS\";|g" \
-      "$1"
+      "$1")" > "$1"
   fi
 }
 
 update_flags /var/www/app/js/config.js
 
-
-
 #########################################
 ## Nginx Config
 #########################################