diff --git a/README.md b/README.md
index b4f6482..bc83709 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,31 @@
 - `GITBUCKET_SSH_PORT`: ssh port to bind to
 
 
+### Update
+Update your gitbucket image in three steps.
+But first of all: **MAKE A BACKUP!!!**
+
+1. Commit your local changes. Changes in `gitbucket.conf` will be ignored!
+
+2. get the new image
+Shutdown and remove your images. This will not delete your mysql database volume.
+```
+docker-compose down
+```
+After that get the new image and start it:
+```
+docker-compose pull
+docker-compose up -d --remove-orphans
+```
+
+3. cleanup your docker environment
+This step is optional. Please do this only if you understand the next line.
+```
+docker rmi -f $(docker images -f "dangling=true" -q)
+```
+
+
+
 ### Plugins
 To use plugins download the plugin and move it into `data/plugins`.
 After that restart the gitbucket container with `docker-compose restart main-gitbucket`.
@@ -54,7 +79,6 @@
 
 
 ## TODO
-- wait for the next update and write an update howto
 - maybe a nginx container with ssl???
 
 
diff --git a/docker-compose.yml b/docker-compose.yml
index e037118..54380ec 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -2,7 +2,7 @@
 
 services:
     main-gitbucket:
-      image: pgollor/gitbucket
+      image: pgollor/gitbucket:4.13
       restart: always
       depends_on:
         - mysql-gitbucket
@@ -13,8 +13,10 @@
         - GITBUCKET_DATABASE_PASSWORD=${GITBUCKET_DATABASE_PASSWORD}
       volumes:
         - ./data/repositories/:/srv/gitbucket/repositories/
-        - ./data/plugins/:/srv/gitbucket/plugins/
+        - ./data/plugins/:/srv/gitbucket/plugins/:ro
         - ./data/conf/gitbucket/gitbucket.conf:/srv/gitbucket/gitbucket.conf
+      tmpfs:
+        - /tmp
       ports:
         - "${GITBUCKET_BIND:-127.0.0.1}:${GITBUCKET_WEB_PORT:-8080}:8080"
         - "${GITBUCKET_BIND:-127.0.0.1}:${GITBUCKET_SSH_PORT:-29418}:29418"
diff --git a/docker/Dockerfile b/docker/Dockerfile
index f2b0c86..cace755 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -16,7 +16,7 @@
 # setup
 RUN apk update
 RUN apk add ca-certificates wget
-RUN wget https://github.com/gitbucket/gitbucket/releases/download/4.12.1/gitbucket.war -O $GITBUCKET_HOME/latest.war
+RUN wget https://github.com/gitbucket/gitbucket/releases/download/4.13/gitbucket.war -O $GITBUCKET_HOME/latest.war
 
 # clean
 RUN apk del ca-certificates wget