diff --git a/router.go b/router.go
index fec4b2f..e61fbae 100644
--- a/router.go
+++ b/router.go
@@ -107,8 +107,6 @@ func convert(c *fiber.Ctx) error {
 		c.Set("Content-Type", "image/avif")
 	}
 
-	etag := genEtag(finalFileName)
-	c.Set("ETag", etag)
 	c.Set("X-Compression-Rate", getCompressionRate(rawImageAbs, finalFileName))
 	return c.SendFile(finalFileName)
 }
diff --git a/router_test.go b/router_test.go
index 8f2a261..8892204 100644
--- a/router_test.go
+++ b/router_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/fiber/v2/middleware/etag"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -31,9 +32,17 @@ func setupParam() {
 }
 
 func requestToServer(url string, app *fiber.App, ua, accept string) (*http.Response, []byte) {
+	headers := make(map[string]string)
+	headers["User-Agent"] = ua
+	headers["Accept"] = accept
+	return requestToServerHeaders(url, app, headers)
+}
+
+func requestToServerHeaders(url string, app *fiber.App, headers map[string]string) (*http.Response, []byte) {
 	req := httptest.NewRequest("GET", url, nil)
-	req.Header.Set("User-Agent", ua)
-	req.Header.Set("Accept", accept)
+	for header, value := range headers {
+		req.Header.Set(header, value)
+	}
 	resp, err := app.Test(req, 120000)
 	if err != nil {
 		return nil, nil
@@ -42,9 +51,13 @@ func requestToServer(url string, app *fiber.App, ua, accept string) (*http.Respo
 	return resp, data
 }
 
+
 func TestServerHeaders(t *testing.T) {
 	setupParam()
 	var app = fiber.New()
+	app.Use(etag.New(etag.Config{
+		Weak: true,
+	}))
 	app.Get("/*", convert)
 	url := "http://127.0.0.1:3333/webp_server.bmp"
 
@@ -53,17 +66,42 @@ func TestServerHeaders(t *testing.T) {
 	defer response.Body.Close()
 	ratio := response.Header.Get("X-Compression-Rate")
 	etag := response.Header.Get("Etag")
+	lastModified := response.Header.Get("Last-Modified")
 
 	assert.NotEqual(t, "", ratio)
 	assert.NotEqual(t, "", etag)
+	assert.NotEqual(t, "", lastModified)
+
+	// TestServerHeadersNotModified
+	var headers = map[string]string{
+		"User-Agent": chromeUA,
+		"Accept": acceptWebP,
+		"If-None-Match": etag,
+	}
+	response, _ = requestToServerHeaders(url, app, headers)
+	defer response.Body.Close()
+	assert.Equal(t, 304, response.StatusCode)
+
+	headers["If-Modified-Since"] = lastModified
+	response, _ = requestToServerHeaders(url, app, headers)
+	defer response.Body.Close()
+	assert.Equal(t, 304, response.StatusCode)
+
+	headers["If-None-Match"] = ""
+	headers["If-Modified-Since"] = lastModified
+	response, _ = requestToServerHeaders(url, app, headers)
+	defer response.Body.Close()
+	assert.Equal(t, 304, response.StatusCode)
 
 	// test for safari
 	response, _ = requestToServer(url, app, safariUA, acceptLegacy)
 	defer response.Body.Close()
 	// ratio = response.Header.Get("X-Compression-Rate")
 	etag = response.Header.Get("Etag")
+	lastModified = response.Header.Get("Last-Modified")
 
 	assert.NotEqual(t, "", etag)
+	assert.NotEqual(t, "", lastModified)
 }
 
 func TestConvert(t *testing.T) {
diff --git a/webp-server.go b/webp-server.go
index d42aa51..e4a1fa1 100644
--- a/webp-server.go
+++ b/webp-server.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/davidbyttow/govips/v2/vips"
 	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/fiber/v2/middleware/etag"
 	"github.com/gofiber/fiber/v2/middleware/logger"
 	log "github.com/sirupsen/logrus"
 )
@@ -111,6 +112,9 @@ Develop by WebP Server team. https://github.com/webp-sh`, version)
 		ServerHeader:          "Webp Server Go",
 		DisableStartupMessage: true,
 	})
+	app.Use(etag.New(etag.Config{
+		Weak: true,
+	}))
 	app.Use(logger.New())
 
 	listenAddress := config.Host + ":" + config.Port