diff --git a/src/docs/user/installation_guide.diviner b/src/docs/user/installation_guide.diviner
index 144aaa03ea..0f02628227 100644
--- a/src/docs/user/installation_guide.diviner
+++ b/src/docs/user/installation_guide.diviner
@@ -87,8 +87,7 @@ You will also need:
   - **git**: You need git 2.5.0 or newer on the server.
     No particular version is needed on your clients.
 
-You'll probably also need a **domain name**. In particular, you should read this
-note:
+You'll probably also need a **domain name**. In particular:
 
 NOTE: Phorge must be installed on an entire domain. You can not install it
 to a path on an existing domain, like `example.com/phorge/`. Instead,
@@ -122,9 +121,10 @@ Here's a general description of what you need to install:
   - Apache (usually "httpd" or "apache2") (or nginx)
   - MySQL Server (usually "mysqld" or "mysql-server" or "mariadb-server")
   - PHP (usually "php")
-  - Required PHP extensions: mbstring, iconv, mysqli, curl, pcntl
+  - Required PHP extensions: mbstring, iconv, mysqli, curl, pcntl, posix
     (these might be something like "php-mysql" or "php-mysqlnd")
-  - Optional PHP extensions: gd, zip
+    (note that "php-posix" is usually included with "php-common" or "php-cli")
+  - Optional PHP extensions: gd, zip, opcache, apcu
 
 If you already have LAMP setup, you've probably already got everything you need.
 It may also be helpful to refer to the install scripts above, even if they don't