diff --git a/changelog/unreleased/web-assets-caching.md b/changelog/unreleased/web-assets-caching.md
index e6fc2547f..7db566fc8 100644
--- a/changelog/unreleased/web-assets-caching.md
+++ b/changelog/unreleased/web-assets-caching.md
@@ -5,3 +5,4 @@ Tags: accounts, settings, web
 We now set http caching headers for static web assets, so that they don't get force-reloaded on each request. The max-age for the caching is configurable and defaults to 7 days. The last modified date of the assets is set to the service start date, so that a service restart results in cache invalidation.
 
 https://github.com/owncloud/ocis/pull/866
+https://github.com/owncloud/ocis/pull/934
diff --git a/ocis-phoenix/pkg/service/v0/service.go b/ocis-phoenix/pkg/service/v0/service.go
index 4bb9942b2..eea57c84a 100644
--- a/ocis-phoenix/pkg/service/v0/service.go
+++ b/ocis-phoenix/pkg/service/v0/service.go
@@ -146,6 +146,7 @@ func (p Phoenix) Static(ttl int) http.HandlerFunc {
 
 	// we don't have a last modification date of the static assets, so we use the service start date
 	lastModified := time.Now().UTC().Format(http.TimeFormat)
+	expires := time.Now().Add(time.Second * time.Duration(ttl)).UTC().Format(http.TimeFormat)
 
 	return func(w http.ResponseWriter, r *http.Request) {
 		if rootWithSlash != "/" && r.URL.Path == p.config.HTTP.Root {
@@ -168,9 +169,9 @@ func (p Phoenix) Static(ttl int) http.HandlerFunc {
 			return
 		}
 
-		w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%s", strconv.Itoa(ttl)))
+		w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%s, must-revalidate", strconv.Itoa(ttl)))
+		w.Header().Set("Expires", expires)
 		w.Header().Set("Last-Modified", lastModified)
-		w.Header().Del("Expires")
 
 		static.ServeHTTP(w, r)
 	}
diff --git a/ocis-pkg/middleware/static.go b/ocis-pkg/middleware/static.go
index 57f2e6957..d601a3eb7 100644
--- a/ocis-pkg/middleware/static.go
+++ b/ocis-pkg/middleware/static.go
@@ -24,15 +24,16 @@ func Static(root string, fs http.FileSystem, ttl int) func(http.Handler) http.Ha
 
 	// we don't have a last modification date of the static assets, so we use the service start date
 	lastModified := time.Now().UTC().Format(http.TimeFormat)
+	expires := time.Now().Add(time.Second * time.Duration(ttl)).UTC().Format(http.TimeFormat)
 
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			if strings.HasPrefix(r.URL.Path, path.Join(root, "api")) {
 				next.ServeHTTP(w, r)
 			} else {
-				w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%s", strconv.Itoa(ttl)))
+				w.Header().Set("Cache-Control", fmt.Sprintf("max-age=%s, must-revalidate", strconv.Itoa(ttl)))
+				w.Header().Set("Expires", expires)
 				w.Header().Set("Last-Modified", lastModified)
-				w.Header().Del("Expires")
 				static.ServeHTTP(w, r)
 			}
 		})