diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index 867641e61..cdbe07f91 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -933,7 +933,7 @@ func NewContext() {
 	newMarkup()
 
 	sec = Cfg.Section("U2F")
-	U2F.TrustedFacets, _ = shellquote.Split(sec.Key("TRUSTED_FACETS").MustString(strings.TrimRight(AppURL, "/")))
+	U2F.TrustedFacets, _ = shellquote.Split(sec.Key("TRUSTED_FACETS").MustString(strings.TrimSuffix(AppURL, AppSubURL+"/")))
 	U2F.AppID = sec.Key("APP_ID").MustString(strings.TrimSuffix(AppURL, "/"))
 
 	UI.ReactionsMap = make(map[string]bool)