diff --git a/src/wp-includes/l10n.php b/src/wp-includes/l10n.php
index ba856491af..30cacf4a67 100644
--- a/src/wp-includes/l10n.php
+++ b/src/wp-includes/l10n.php
@@ -28,7 +28,7 @@
  * @return string The locale of the blog or from the {@see 'locale'} hook.
  */
 function get_locale() {
-	global $locale, $wp_local_package;
+	global $locale, $wp_local_package, $wpdb;
 
 	if ( isset( $locale ) ) {
 		/**
@@ -50,6 +50,15 @@ function get_locale() {
 		$locale = WPLANG;
 	}
 
+	// If $wpdb hasn't been initialised yet, we can only return what we have.
+	if ( ! $wpdb ) {
+		if ( ! $locale ) {
+			return 'en_US';
+		}
+
+		return $locale;
+	}
+
 	// If multisite, check options.
 	if ( is_multisite() ) {
 		// Don't check blog option when installing.
diff --git a/tests/phpunit/tests/l10n/getLocale.php b/tests/phpunit/tests/l10n/getLocale.php
index 64b9900ab4..e7dc7255ab 100644
--- a/tests/phpunit/tests/l10n/getLocale.php
+++ b/tests/phpunit/tests/l10n/getLocale.php
@@ -81,6 +81,40 @@ class Tests_L10n_GetLocale extends WP_UnitTestCase {
 		$this->assertSame( 'en_US', $found );
 	}
 
+	public function test_should_fall_back_on_locale_when_wpdb_is_unavailable() {
+		global $locale, $wpdb;
+
+		$old_locale = $locale;
+		$old_wpdb = $wpdb;
+
+		$locale = $expected = "Is this a locale? No. No it isn't.";
+		$wpdb = null;
+
+		$found = get_locale();
+
+		$locale = $old_locale;
+		$wpdb = $old_wpdb;
+
+		$this->assertSame( $expected, $found );
+	}
+
+	public function test_should_fall_back_on_es_US_when_locale_and_wpdb_are_unavailable() {
+		global $locale, $wpdb;
+
+		$old_locale = $locale;
+		$old_wpdb = $wpdb;
+
+		$locale = null;
+		$wpdb = null;
+
+		$found = get_locale();
+
+		$locale = $old_locale;
+		$wpdb = $old_wpdb;
+
+		$this->assertSame( 'en_US', $found );
+	}
+
 	public function test_should_respect_get_locale_filter() {
 		add_filter( 'locale', array( $this, 'filter_get_locale' ) );
 		$found = get_locale();