diff --git a/Dockerfile b/Dockerfile
index f4579e13..9abac691 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -22,7 +22,7 @@ COPY --chown=sydent:sydent ["README.rst", "setup.cfg", "setup.py", "/sydent/"]
 
 # Install dependencies
 RUN cd /sydent \
-    && su sydent -c 'pip install --user --upgrade pip setuptools sentry-sdk' \
+    && su sydent -c 'pip install --user --upgrade pip setuptools sentry-sdk prometheus_client' \
     && su sydent -c 'pip install --user -e .' \
     && rm -rf /sydent/.cache \
     && find /sydent -name '*.pyc' -delete
diff --git a/changelog.d/325.misc b/changelog.d/325.misc
new file mode 100644
index 00000000..2db91423
--- /dev/null
+++ b/changelog.d/325.misc
@@ -0,0 +1 @@
+Install prometheus_client in the Docker image.