diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 8fd41940e96dbb6474e30056d9c70ba94861ee1e..69fbdedcdf97a48c13391dc418c3bbe96454dd7f 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -14,6 +14,8 @@ Fixed
 
 * The menu button used to be displayed twice on smaller screens.
 * The icons were loaded from external servers instead from local server.
+* Weekdays were not translated if system locales were missing
+  * Added locales-all to base image and note to docs
 
 Changed
 ~~~~~~~
diff --git a/Dockerfile b/Dockerfile
index acb08f98ffe79dccc32f048590bb123c2763302f..4864ac54613a8823fbc118fe73291e127b7939e1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -36,6 +36,7 @@ RUN apt-get -y update && \
         less \
 	libpq-dev \
 	libssl-dev \
+	locales-all \
 	postgresql-client-14 \
         pspg \
 	python3-dev \
diff --git a/docs/admin/10_install.rst b/docs/admin/10_install.rst
index d41bd44e56c1fd85208467e9849d448d960c1900..f8b41d0d98efd5daa1df64a5fceea9ae5b86c662 100644
--- a/docs/admin/10_install.rst
+++ b/docs/admin/10_install.rst
@@ -34,6 +34,7 @@ For an installation on a dedicated server, the following prerequisites are neede
  * nginx
  * Python 3.9
  * Some system dependencies to build Python modules and manage frontend files
+ * System locales for all supported languages
  * The aforementioned paths
 
 Install system packages
@@ -53,7 +54,8 @@ Install some packages from the Debian package system.
                python3-virtualenv \
                chromium \
                redis-server \
-               postgresql
+               postgresql \
+               locales-all
 
 Create PostgreSQL user and database
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~