diff --git a/server/gitea/cache.go b/server/gitea/cache.go
index 0b7f702..ccc75b4 100644
--- a/server/gitea/cache.go
+++ b/server/gitea/cache.go
@@ -57,7 +57,7 @@ func (f FileResponse) createHttpResponse(cacheKey string) (http.Header, int) {
 	}
 	header.Set(ETagHeader, f.ETag)
 	header.Set(ContentTypeHeader, f.MimeType)
-	header.Set(ContentLengthHeader, fmt.Sprint(len(f.Body)))
+	header.Set(ContentLengthHeader, fmt.Sprintf("%d", len(f.Body)))
 	header.Set(PagesCacheIndicatorHeader, "true")
 
 	log.Trace().Msgf("fileCache for '%s' used", cacheKey)
diff --git a/server/upstream/upstream.go b/server/upstream/upstream.go
index e8997c9..689c1db 100644
--- a/server/upstream/upstream.go
+++ b/server/upstream/upstream.go
@@ -157,13 +157,19 @@ func (o *Options) Upstream(ctx *context.Context, giteaClient *gitea.Client) (fin
 	log.Debug().Msg("Handling error")
 
 	// Set ETag & MIME
-	ctx.RespWriter.Header().Set(gitea.ETagHeader, header.Get(gitea.ETagHeader))
-	ctx.RespWriter.Header().Set(gitea.PagesCacheIndicatorHeader, header.Get(gitea.PagesCacheIndicatorHeader))
-	ctx.RespWriter.Header().Set(gitea.ContentLengthHeader, header.Get(gitea.ContentLengthHeader))
-	if o.ServeRaw {
+	if eTag := header.Get(gitea.ETagHeader); eTag != "" {
+		ctx.RespWriter.Header().Set(gitea.ETagHeader, eTag)
+	}
+	if cacheIndicator := header.Get(gitea.PagesCacheIndicatorHeader); cacheIndicator != "" {
+		ctx.RespWriter.Header().Set(gitea.PagesCacheIndicatorHeader, cacheIndicator)
+	}
+	if length := header.Get(gitea.ContentLengthHeader); length != "" {
+		ctx.RespWriter.Header().Set(gitea.ContentLengthHeader, length)
+	}
+	if mime := header.Get(gitea.ContentTypeHeader); mime == "" || o.ServeRaw {
 		ctx.RespWriter.Header().Set(gitea.ContentTypeHeader, rawMime)
 	} else {
-		ctx.RespWriter.Header().Set(gitea.ContentTypeHeader, header.Get(gitea.ContentTypeHeader))
+		ctx.RespWriter.Header().Set(gitea.ContentTypeHeader, mime)
 	}
 
 	if ctx.StatusCode != http.StatusNotFound {