diff --git a/src/docs/installation_guide.diviner b/src/docs/installation_guide.diviner
index 449ea71bd2..60904b0b23 100644
--- a/src/docs/installation_guide.diviner
+++ b/src/docs/installation_guide.diviner
@@ -41,7 +41,7 @@ Otherwise, here's a general description of what you need to install:
   - Apache (usually "httpd" or "apache2")
   - MySQL Server (usually "mysqld" or "mysql-server")
   - PHP (usually "php")
-  - Required PHP extensions: mysql, curl, pcntl (these might be something like
+  - Required PHP extensions: mbstring, iconv, mysql, curl, pcntl (these might be something like
     "php-mysql" or "php5-mysql")
   - Optional PHP extensions: gd, apc (special instructions for APC are available
     below if you have difficulty installing it), xhprof (instructions below,
diff --git a/src/infrastructure/setup/PhabricatorSetup.php b/src/infrastructure/setup/PhabricatorSetup.php
index 7fc9c1784c..38c7c94f4d 100644
--- a/src/infrastructure/setup/PhabricatorSetup.php
+++ b/src/infrastructure/setup/PhabricatorSetup.php
@@ -130,6 +130,8 @@ class PhabricatorSetup {
       'hash',
       'json',
       'openssl',
+      'mbstring',
+      'iconv',
 
       // There is a chance we might not need this, but some configurations (like
       // Amazon SES) will require it. Just mark it 'required' since it's widely