diff --git a/pages/index.go b/pages/index.go
index 7bacf54..e47b4b2 100644
--- a/pages/index.go
+++ b/pages/index.go
@@ -95,7 +95,7 @@ func HandleIndex(c *fiber.Ctx) error {
 	defaultLang := os.Getenv("MOZHI_DEFAULT_SOURCE_LANG")
 	preferAutoDetect := os.Getenv("MOZHI_DEFAULT_PREFER_AUTODETECT")
 	defaultLangTarget := os.Getenv("MOZHI_DEFAULT_TARGET_LANG")
-	if defaultLang == "" || preferAutoDetect == "true" {
+	if defaultLang == "" || (preferAutoDetect == "true" && sourceLanguages[0].Id == "auto") {
 		defaultLang = "auto"
 	}
 	if defaultLangTarget == "" {
diff --git a/views/index.html b/views/index.html
index 05dc39c..cc68bf2 100644
--- a/views/index.html
+++ b/views/index.html
@@ -21,11 +21,11 @@
       <div class="language">
         <select name="from" aria-label="Source language" id="sourceLanguage">
           {{ range $key, $value := .SourceLanguages }} {{ if eq $.From "" }}
-          <option value="{{ .Id }}" {{ if eq $.From .Id }}selected{{ end }}>
+          <option value="{{ .Id }}" {{ if eq .Id $.defaultLang }}selected{{ end }}>
             {{ .Name }}
           </option>
         {{ else }}
-          <option value="{{ .Id }}" {{ if eq .Id $.defaultLang }}selected{{ end }}>
+          <option value="{{ .Id }}" {{ if eq $.From .Id }}selected{{ end }}>
             {{ .Name }}
           </option>
           {{ end }} {{ end }}