diff --git a/src/e-util/e-misc-utils.c b/src/e-util/e-misc-utils.c
index aa90fc0b12..68e427d260 100644
--- a/src/e-util/e-misc-utils.c
+++ b/src/e-util/e-misc-utils.c
@@ -4506,7 +4506,7 @@ e_util_enum_supported_locales (void)
 		catalog_filename = g_build_filename (EVOLUTION_LOCALEDIR, e_supported_locales[ii].code, "LC_MESSAGES", GETTEXT_PACKAGE ".mo", NULL);
 
 		if (catalog_filename && g_file_test (catalog_filename, G_FILE_TEST_EXISTS)) {
-			g_string_printf (locale, "%s.utf8", e_supported_locales[ii].locale);
+			g_string_printf (locale, "%s.UTF-8", e_supported_locales[ii].locale);
 
 			if (!setlocale (category, locale->str)) {
 				e_supported_locales[ii].locale = NULL;
diff --git a/src/mail/em-composer-utils.c b/src/mail/em-composer-utils.c
index f48bfd9d13..92a6c85c76 100644
--- a/src/mail/em-composer-utils.c
+++ b/src/mail/em-composer-utils.c
@@ -1959,10 +1959,10 @@ emcu_prepare_attribution_locale (ESource *identity_source,
 	}
 
 	if (lang) {
-		if (!strchr (lang, '.')) {
+		if (!g_str_equal (lang, "C") && !strchr (lang, '.')) {
 			gchar *tmp;
 
-			tmp = g_strconcat (lang, ".utf8", NULL);
+			tmp = g_strconcat (lang, ".UTF-8", NULL);
 			g_free (lang);
 			lang = tmp;
 		}
diff --git a/src/modules/mail/em-composer-prefs.c b/src/modules/mail/em-composer-prefs.c
index b411599595..7b4ad40cb5 100644
--- a/src/modules/mail/em-composer-prefs.c
+++ b/src/modules/mail/em-composer-prefs.c
@@ -1337,7 +1337,7 @@ em_composer_prefs_construct (EMComposerPrefs *prefs,
 		G_SETTINGS_BIND_DEFAULT);
 
 	widget = e_builder_get_widget (prefs->builder, "comboboxForwardReplyAttribLanguage");
-	gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (widget), NULL, _("Same as user interface"));
+	gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (widget), "", _("Same as user interface"));
 	em_utils_add_installed_languages (GTK_COMBO_BOX_TEXT (widget));
 
 	g_settings_bind (