diff --git a/cache.go b/cache.go
index feeecc1..b8b2bf9 100644
--- a/cache.go
+++ b/cache.go
@@ -1,14 +1,16 @@
 package main
 
 import (
+	"bytes"
+	"crypto/sha256"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"strconv"
 	"time"
 
-	"github.com/araddon/dateparse"
 	lru "github.com/hashicorp/golang-lru"
 	"golang.org/x/sync/singleflight"
 )
@@ -40,25 +42,21 @@ func cacheMiddleware(next http.Handler) http.Handler {
 				return getCache(key, next, r), nil
 			})
 			cache := cacheInterface.(*cacheItem)
-			cacheTimeString := time.Unix(cache.creationTime, 0).Format(time.RFC1123)
-			expiresTimeString := ""
+			var expiresIn int64 = 0
 			if cache.expiration != 0 {
-				expiresTimeString = time.Unix(cache.creationTime+int64(cache.expiration), 0).Format(time.RFC1123)
-			}
-			// check conditional request
-			if ifModifiedSinceHeader := r.Header.Get("If-Modified-Since"); ifModifiedSinceHeader != "" {
-				if t, _ := dateparse.ParseIn(ifModifiedSinceHeader, time.Local); t.Unix() == cache.creationTime {
-					// send 304
-					setCacheHeaders(w, cacheTimeString, expiresTimeString)
-					w.WriteHeader(http.StatusNotModified)
-					return
-				}
+				expiresIn = cache.creationTime + int64(cache.expiration) - time.Now().Unix()
 			}
 			// copy cached headers
 			for k, v := range cache.header {
 				w.Header()[k] = v
 			}
-			setCacheHeaders(w, cacheTimeString, expiresTimeString)
+			setCacheHeaders(w, cache.hash, expiresIn)
+			// check conditional request
+			if ifNoneMatchHeader := r.Header.Get("If-None-Match"); ifNoneMatchHeader != "" && ifNoneMatchHeader == cache.hash {
+				// send 304
+				w.WriteHeader(http.StatusNotModified)
+				return
+			}
 			// set status code
 			w.WriteHeader(cache.code)
 			// write cached body
@@ -74,21 +72,21 @@ func cacheKey(r *http.Request) string {
 	return r.URL.String()
 }
 
-func setCacheHeaders(w http.ResponseWriter, cacheTimeString string, expiresTimeString string) {
+func setCacheHeaders(w http.ResponseWriter, hash string, expiresIn int64) {
 	w.Header().Del(cacheInternalExpirationHeader)
-	w.Header().Set("Last-Modified", cacheTimeString)
-	if expiresTimeString != "" {
+	w.Header().Set("ETag", hash)
+	if expiresIn != 0 {
 		// Set expires time
-		w.Header().Set("Cache-Control", "public")
-		w.Header().Set("Expires", expiresTimeString)
+		w.Header().Set("Cache-Control", fmt.Sprintf("public,max-age=%d", expiresIn))
 	} else {
 		w.Header().Set("Cache-Control", fmt.Sprintf("public,max-age=%d,s-max-age=%d", appConfig.Cache.Expiration, appConfig.Cache.Expiration/3))
 	}
 }
 
 type cacheItem struct {
-	creationTime int64
 	expiration   int
+	creationTime int64
+	hash         string
 	code         int
 	header       http.Header
 	body         []byte
@@ -113,10 +111,15 @@ func getCache(key string, next http.Handler, r *http.Request) (item *cacheItem)
 		// Cache values from recorder
 		result := recorder.Result()
 		body, _ := ioutil.ReadAll(result.Body)
+		_ = result.Body.Close()
+		h := sha256.New()
+		_, _ = io.Copy(h, bytes.NewReader(body))
+		hash := fmt.Sprintf("%x", h.Sum(nil))
 		exp, _ := strconv.Atoi(result.Header.Get(cacheInternalExpirationHeader))
 		item = &cacheItem{
-			creationTime: time.Now().Unix(),
 			expiration:   exp,
+			creationTime: time.Now().Unix(),
+			hash:         hash,
 			code:         result.StatusCode,
 			header:       result.Header,
 			body:         body,