diff --git a/wp-admin/includes/upgrade.php b/wp-admin/includes/upgrade.php
index 2957d52ca1..60077a83ef 100644
--- a/wp-admin/includes/upgrade.php
+++ b/wp-admin/includes/upgrade.php
@@ -1277,6 +1277,16 @@ function upgrade_network() {
 	// 3.5
 	if ( $wp_current_db_version < 21823 )
 		update_site_option( 'ms_files_rewriting', '1' );
+
+	// 3.5.2
+	if ( $wp_current_db_version < 24448 ) {
+		$illegal_names = get_site_option( 'illegal_names' );
+		if ( is_array( $illegal_names ) && count( $illegal_names ) === 1 ) {
+			$illegal_name = reset( $illegal_names );
+			$illegal_names = explode( ' ', $illegal_name );
+			update_site_option( 'illegal_names', $illegal_names );
+		}
+	}
 }
 
 // The functions we use to actually do stuff
diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 512accbe9f..7dc914223a 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -2901,7 +2901,7 @@ function sanitize_option($option, $value) {
 
 		case 'illegal_names':
 			if ( ! is_array( $value ) )
-				$value = explode( "\n", $value );
+				$value = explode( ' ', $value );
 
 			$value = array_values( array_filter( array_map( 'trim', $value ) ) );
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3aff87aa69..551d6f395a 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -11,7 +11,7 @@ $wp_version = '3.6-beta3-24432';
  *
  * @global int $wp_db_version
  */
-$wp_db_version = 23588;
+$wp_db_version = 24448;
 
 /**
  * Holds the TinyMCE version