diff --git a/modules/httpcache/httpcache.go b/modules/httpcache/httpcache.go
index 40458dfc33..2c9af94405 100644
--- a/modules/httpcache/httpcache.go
+++ b/modules/httpcache/httpcache.go
@@ -75,7 +75,8 @@ func HandleGenericETagTimeCache(req *http.Request, w http.ResponseWriter, etag s
 		w.Header().Set("Etag", etag)
 	}
 	if lastModified != nil && !lastModified.IsZero() {
-		w.Header().Set("Last-Modified", lastModified.Format(http.TimeFormat))
+		// http.TimeFormat required a UTC time, refer to https://pkg.go.dev/net/http#TimeFormat
+		w.Header().Set("Last-Modified", lastModified.UTC().Format(http.TimeFormat))
 	}
 
 	if len(etag) > 0 {
diff --git a/modules/httplib/serve.go b/modules/httplib/serve.go
index 6e147d76f5..2e3e6a7c42 100644
--- a/modules/httplib/serve.go
+++ b/modules/httplib/serve.go
@@ -79,6 +79,7 @@ func ServeSetHeaders(w http.ResponseWriter, opts *ServeHeaderOptions) {
 	httpcache.SetCacheControlInHeader(header, duration)
 
 	if !opts.LastModified.IsZero() {
+		// http.TimeFormat required a UTC time, refer to https://pkg.go.dev/net/http#TimeFormat
 		header.Set("Last-Modified", opts.LastModified.UTC().Format(http.TimeFormat))
 	}
 }
diff --git a/routers/api/packages/maven/maven.go b/routers/api/packages/maven/maven.go
index 07e34da8e2..343705990a 100644
--- a/routers/api/packages/maven/maven.go
+++ b/routers/api/packages/maven/maven.go
@@ -115,7 +115,9 @@ func serveMavenMetadata(ctx *context.Context, params parameters) {
 	xmlMetadataWithHeader := append([]byte(xml.Header), xmlMetadata...)
 
 	latest := pds[len(pds)-1]
-	ctx.Resp.Header().Set("Last-Modified", latest.Version.CreatedUnix.Format(http.TimeFormat))
+	// http.TimeFormat required a UTC time, refer to https://pkg.go.dev/net/http#TimeFormat
+	lastModifed := latest.Version.CreatedUnix.AsTime().UTC().Format(http.TimeFormat)
+	ctx.Resp.Header().Set("Last-Modified", lastModifed)
 
 	ext := strings.ToLower(filepath.Ext(params.Filename))
 	if isChecksumExtension(ext) {
diff --git a/routers/web/repo/githttp.go b/routers/web/repo/githttp.go
index bb85df1a86..ee1ec1fd0c 100644
--- a/routers/web/repo/githttp.go
+++ b/routers/web/repo/githttp.go
@@ -395,7 +395,8 @@ func (h *serviceHandler) sendFile(ctx *context.Context, contentType, file string
 
 	ctx.Resp.Header().Set("Content-Type", contentType)
 	ctx.Resp.Header().Set("Content-Length", fmt.Sprintf("%d", fi.Size()))
-	ctx.Resp.Header().Set("Last-Modified", fi.ModTime().Format(http.TimeFormat))
+	// http.TimeFormat required a UTC time, refer to https://pkg.go.dev/net/http#TimeFormat
+	ctx.Resp.Header().Set("Last-Modified", fi.ModTime().UTC().Format(http.TimeFormat))
 	http.ServeFile(ctx.Resp, ctx.Req, reqFile)
 }