diff --git a/wp-includes/l10n.php b/wp-includes/l10n.php
index 30cacf4a67..2c227bc1da 100644
--- a/wp-includes/l10n.php
+++ b/wp-includes/l10n.php
@@ -53,10 +53,11 @@ function get_locale() {
 	// If $wpdb hasn't been initialised yet, we can only return what we have.
 	if ( ! $wpdb ) {
 		if ( ! $locale ) {
-			return 'en_US';
+			$locale = 'en_US';
 		}
 
-		return $locale;
+		/** This filter is documented in wp-includes/l10n.php */
+		return apply_filters( 'locale', $locale );
 	}
 
 	// If multisite, check options.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index f28e9397e6..211eff38d3 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38977';
+$wp_version = '4.7-alpha-38978';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.