diff --git a/httpServer.go b/httpServer.go
index 5f7c67c..9354ea9 100644
--- a/httpServer.go
+++ b/httpServer.go
@@ -11,6 +11,9 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+const dataFilename = "data-server.json"
+const outputFilename = "syncthing-map-server.html"
+
 // configuration file for each device and the folder holding config.xml
 type serverConfigT []struct {
 	Device string
@@ -18,21 +21,10 @@ type serverConfigT []struct {
 }
 
 func httpServer() {
-	const dataFilename = "data-server.json"
-	const outputFilename = "syncthing-map-server.html"
-
 	r := chi.NewRouter()
 	r.Use(middleware.Logger)
 	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
-		conf := readServerConf()
-		// recreate a data file with each server
-		os.Remove(dataFilename)
-		for _, entry := range conf {
-			readConfigXml(entry.Device, filepath.Join(entry.Folder, "config.xml"), dataFilename)
-			log.Info().Msgf("parsed configuration for %s", entry.Device)
-		}
-		// write HTML file to serve
-		writeGraph(dataFilename, outputFilename)
+		writeHtmlFile()
 		response, err := readFile(outputFilename)
 		if err != nil {
 			log.Error().Msgf("cannot read generated file: %v", err)
@@ -42,6 +34,8 @@ func httpServer() {
 			w.Write(response)
 		}
 	})
+	// write output file at start
+	writeHtmlFile()
 	log.Info().Msg("starting server on port 3000")
 	http.ListenAndServe(":3000", r)
 }
@@ -57,3 +51,15 @@ func readServerConf() (conf serverConfigT) {
 	}
 	return conf
 }
+
+func writeHtmlFile() {
+	conf := readServerConf()
+	// recreate a data file with each server
+	os.Remove(dataFilename)
+	for _, entry := range conf {
+		readConfigXml(entry.Device, filepath.Join(entry.Folder, "config.xml"), dataFilename)
+		log.Info().Msgf("parsed configuration for %s", entry.Device)
+	}
+	// write HTML file to serve
+	writeGraph(dataFilename, outputFilename)
+}