diff --git a/wp-admin/network/plugin-install.php b/wp-admin/network/plugin-install.php
index abfef634f7..5c6243f1cf 100644
--- a/wp-admin/network/plugin-install.php
+++ b/wp-admin/network/plugin-install.php
@@ -7,6 +7,9 @@
  * @since 3.1.0
  */
 
+if ( isset( $_GET['tab'] ) && ( 'plugin-information' == $_GET['tab'] ) )
+	define( 'IFRAME_REQUEST', true );
+
 /** Load WordPress Administration Bootstrap */
 require_once( './admin.php' );
 
diff --git a/wp-admin/network/theme-install.php b/wp-admin/network/theme-install.php
index 4cec1914ab..bc4e6269aa 100644
--- a/wp-admin/network/theme-install.php
+++ b/wp-admin/network/theme-install.php
@@ -7,6 +7,9 @@
  * @since 3.1.0
  */
 
+if ( isset( $_GET['tab'] ) && ( 'theme-information' == $_GET['tab'] ) )
+	define( 'IFRAME_REQUEST', true );
+
 /** Load WordPress Administration Bootstrap */
 require_once( './admin.php' );
 
diff --git a/wp-admin/plugin-install.php b/wp-admin/plugin-install.php
index cbdb055cd6..55fc9f6cee 100644
--- a/wp-admin/plugin-install.php
+++ b/wp-admin/plugin-install.php
@@ -6,8 +6,8 @@
  * @subpackage Administration
  */
 // TODO route this pages via a specific iframe handler instead of the do_action below
-if ( isset( $_GET['tab'] ) && ( 'plugin-information' == $_GET['tab'] ) )
-	define('IFRAME_REQUEST' , true);
+if ( !defined( 'IFRAME_REQUEST' ) && isset( $_GET['tab'] ) && ( 'plugin-information' == $_GET['tab'] ) )
+	define( 'IFRAME_REQUEST', true );
 
 /** WordPress Administration Bootstrap */
 require_once('./admin.php');
diff --git a/wp-admin/theme-install.php b/wp-admin/theme-install.php
index f4b6301970..779a0374ee 100644
--- a/wp-admin/theme-install.php
+++ b/wp-admin/theme-install.php
@@ -6,7 +6,7 @@
  * @subpackage Administration
  */
 
-if ( isset( $_GET['tab'] ) && ( 'theme-information' == $_GET['tab'] ) )
+if ( !defined( 'IFRAME_REQUEST' ) && isset( $_GET['tab'] ) && ( 'theme-information' == $_GET['tab'] ) )
 	define( 'IFRAME_REQUEST', true );
 	
 /** WordPress Administration Bootstrap */