diff --git a/src/wp-includes/class-wp-textdomain-registry.php b/src/wp-includes/class-wp-textdomain-registry.php
index 4121ecb091..8ff8ad0ae2 100644
--- a/src/wp-includes/class-wp-textdomain-registry.php
+++ b/src/wp-includes/class-wp-textdomain-registry.php
@@ -237,13 +237,13 @@ class WP_Textdomain_Registry {
 		foreach ( $translation_types as $type ) {
 			switch ( $type ) {
 				case 'plugin':
-					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins' ), 'translations' );
+					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins/' ), 'translations' );
 					break;
 				case 'theme':
-					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes' ), 'translations' );
+					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes/' ), 'translations' );
 					break;
 				default:
-					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR ), 'translations' );
+					wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/' ), 'translations' );
 					break;
 			}
 		}
diff --git a/tests/phpunit/tests/l10n/wpTextdomainRegistry.php b/tests/phpunit/tests/l10n/wpTextdomainRegistry.php
index 8334c4ea2e..19a239428d 100644
--- a/tests/phpunit/tests/l10n/wpTextdomainRegistry.php
+++ b/tests/phpunit/tests/l10n/wpTextdomainRegistry.php
@@ -19,10 +19,10 @@ class Tests_L10n_wpTextdomainRegistry extends WP_UnitTestCase {
 	}
 
 	public function tear_down() {
-		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/foobar' ), 'translations' );
-		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins' ), 'translations' );
-		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes' ), 'translations' );
-		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR ), 'translations' );
+		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/foobar/' ), 'translations' );
+		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins/' ), 'translations' );
+		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes/' ), 'translations' );
+		wp_cache_delete( 'cached_mo_files_' . md5( WP_LANG_DIR . '/' ), 'translations' );
 
 		parent::tear_down();
 	}
@@ -100,10 +100,10 @@ class Tests_L10n_wpTextdomainRegistry extends WP_UnitTestCase {
 	 */
 	public function test_get_language_files_from_path_short_circuit() {
 		add_filter( 'pre_get_language_files_from_path', '__return_empty_array' );
-		$result = $this->instance->get_language_files_from_path( WP_LANG_DIR . '/plugins' );
+		$result = $this->instance->get_language_files_from_path( WP_LANG_DIR . '/plugins/' );
 		remove_filter( 'pre_get_language_files_from_path', '__return_empty_array' );
 
-		$cache = wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins' ), 'translations' );
+		$cache = wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins/' ), 'translations' );
 
 		$this->assertEmpty( $result );
 		$this->assertFalse( $cache );
@@ -113,9 +113,9 @@ class Tests_L10n_wpTextdomainRegistry extends WP_UnitTestCase {
 	 * @covers ::invalidate_mo_files_cache
 	 */
 	public function test_invalidate_mo_files_cache() {
-		$this->instance->get_language_files_from_path( WP_LANG_DIR . '/plugins' );
-		$this->instance->get_language_files_from_path( WP_LANG_DIR . '/themes' );
-		$this->instance->get_language_files_from_path( WP_LANG_DIR );
+		$this->instance->get_language_files_from_path( WP_LANG_DIR . '/plugins/' );
+		$this->instance->get_language_files_from_path( WP_LANG_DIR . '/themes/' );
+		$this->instance->get_language_files_from_path( WP_LANG_DIR . '/' );
 
 		$this->instance->invalidate_mo_files_cache(
 			null,
@@ -144,9 +144,9 @@ class Tests_L10n_wpTextdomainRegistry extends WP_UnitTestCase {
 			)
 		);
 
-		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins' ), 'translations' ) );
-		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes' ), 'translations' ) );
-		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR ), 'translations' ) );
+		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/plugins/' ), 'translations' ) );
+		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/themes/' ), 'translations' ) );
+		$this->assertFalse( wp_cache_get( 'cached_mo_files_' . md5( WP_LANG_DIR . '/' ), 'translations' ) );
 	}
 
 	public function data_domains_locales() {