diff --git a/CHANGELOG.md b/CHANGELOG.md
index bec10fb..07eaf74 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -777,5 +777,5 @@
 
 [1.56.0]
 * Update Synapse to 1.73.0
+* Update Cloudron base image to 4.0.0
 * [Full changelog](https://github.com/matrix-org/synapse/releases/tag/v1.73.0)
-
diff --git a/Dockerfile b/Dockerfile
index fa0777f..557b1b6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
-FROM cloudron/base:3.2.0@sha256:ba1d566164a67c266782545ea9809dc611c4152e27686fd14060332dd88263ea
- 
+FROM cloudron/base:4.0.0@sha256:31b195ed0662bdb06a6e8a5ddbedb6f191ce92e8bee04c03fb02dd4e9d0286df
+
 RUN mkdir -p /app/pkg
 
 WORKDIR /app/code
@@ -17,7 +17,7 @@ RUN pip install --upgrade pip && \
     pip install --upgrade setuptools && \
     pip install matrix-synapse==${VERSION} psycopg2-binary python-ldap matrix-synapse-ldap3 lxml publicsuffix2 git+https://github.com/matrix-org/synapse-s3-storage-provider.git@ffd3fa477321608e57d27644197e721965e0e858 matrix-synapse[oidc]
 
-RUN ln -sf /app/data/index.html /app/code/env/lib/python3.8/site-packages/synapse/static/index.html
+RUN ln -sf /app/data/index.html /app/code/env/lib/python3.10/site-packages/synapse/static/index.html
 
 RUN chown -R cloudron.cloudron /app/code