diff --git a/wp-includes/formatting.php b/wp-includes/formatting.php
index 1e8c59835d..9edea6a704 100644
--- a/wp-includes/formatting.php
+++ b/wp-includes/formatting.php
@@ -1482,35 +1482,34 @@ function backslashit($string) {
 /**
  * Appends a trailing slash.
  *
- * Will remove trailing slash if it exists already before adding a trailing
- * slash. This prevents double slashing a string or path.
+ * Will remove trailing forward and backslashes if it exists already before adding
+ * a trailing forward slash. This prevents double slashing a string or path.
  *
  * The primary use of this is for paths and thus should be used for paths. It is
  * not restricted to paths and offers no specific path support.
  *
  * @since 1.2.0
- * @uses untrailingslashit() Unslashes string if it was slashed already.
  *
  * @param string $string What to add the trailing slash to.
  * @return string String with trailing slash added.
  */
-function trailingslashit($string) {
-	return untrailingslashit($string) . '/';
+function trailingslashit( $string ) {
+	return untrailingslashit( $string ) . '/';
 }
 
 /**
- * Removes trailing slash if it exists.
+ * Removes trailing forward slashes and backslashes if they exist.
  *
  * The primary use of this is for paths and thus should be used for paths. It is
  * not restricted to paths and offers no specific path support.
  *
  * @since 2.2.0
  *
- * @param string $string What to remove the trailing slash from.
- * @return string String without the trailing slash.
+ * @param string $string What to remove the trailing slashes from.
+ * @return string String without the trailing slashes.
  */
-function untrailingslashit($string) {
-	return rtrim($string, '/');
+function untrailingslashit( $string ) {
+	return rtrim( $string, '/\\' );
 }
 
 /**
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index c5a9fea79f..0e34a5e5d4 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1455,17 +1455,17 @@ function get_temp_dir() {
 		return trailingslashit(WP_TEMP_DIR);
 
 	if ( $temp )
-		return trailingslashit( rtrim( $temp, '\\' ) );
+		return trailingslashit( $temp );
 
 	if ( function_exists('sys_get_temp_dir') ) {
 		$temp = sys_get_temp_dir();
 		if ( @is_dir( $temp ) && wp_is_writable( $temp ) )
-			return trailingslashit( rtrim( $temp, '\\' ) );
+			return trailingslashit( $temp );
 	}
 
 	$temp = ini_get('upload_tmp_dir');
 	if ( @is_dir( $temp ) && wp_is_writable( $temp ) )
-		return trailingslashit( rtrim( $temp, '\\' ) );
+		return trailingslashit( $temp );
 
 	$temp = WP_CONTENT_DIR . '/';
 	if ( is_dir( $temp ) && wp_is_writable( $temp ) )