diff --git a/internal/server/static_delivery.go b/internal/server/static_delivery.go
new file mode 100644
index 00000000..216b7314
--- /dev/null
+++ b/internal/server/static_delivery.go
@@ -0,0 +1,18 @@
+package server
+
+import (
+	"net/http"
+	"strings"
+)
+
+//nolint:unused
+func addVary(header http.Header, value string) {
+	for _, line := range header.Values("Vary") {
+		for _, existing := range strings.Split(line, ",") {
+			if strings.EqualFold(strings.TrimSpace(existing), value) {
+				return
+			}
+		}
+	}
+	header.Add("Vary", value)
+}