diff --git a/wp-admin/includes/file.php b/wp-admin/includes/file.php
index 1250e36f6f..6bb61cff4e 100644
--- a/wp-admin/includes/file.php
+++ b/wp-admin/includes/file.php
@@ -168,7 +168,7 @@ function wp_tempnam( $filename = '', $dir = '' ) {
 		$dir = get_temp_dir();
 	}
 
-	if ( empty( $filename ) || '.' == $filename || '/' == $filename ) {
+	if ( empty( $filename ) || '.' == $filename || '/' == $filename || '\\' == $filename ) {
 		$filename = time();
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3339b75210..71a2b12716 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-beta4-38150';
+$wp_version = '4.6-beta4-38151';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.