diff --git a/README b/README
index 39721e2cf8..228d0b1d08 100644
--- a/README
+++ b/README
@@ -126,6 +126,7 @@ Your PHP installation must include the following PHP extensions:
 - MySQL. For accessing the database.
 - GD. For scaling down avatar images.
 - mbstring. For handling Unicode (UTF-8) encoded strings.
+- gettext. For multiple languages. Default on many PHP installs.
 
 For some functionality, you will also need the following extensions: