diff --git a/docs/installation.rst b/docs/installation.rst
index c06dec78..7bb5bb08 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -216,7 +216,8 @@ of ``pip`` at ``/usr/local/bin/pip``.
 **Install OCRmyPDF**
 
 OCRmyPDF requires the locale to be set for UTF-8. **On some minimal
-Ubuntu installations systems**, it may be necessary to set the locale.
+Ubuntu installations**, such as the Ubuntu 16.04 Docker images it may be
+necessary to set the locale.
 
 .. code-block:: bash