diff --git a/server.go b/server.go
index 0bd34ec..fcd04c6 100644
--- a/server.go
+++ b/server.go
@@ -68,7 +68,7 @@ func (*Response[RSB]) ResponseBuilder() ResponseBuilder {
 type ResponseBuilder interface {
 	mustEmbedDefaultResponseBuilder()
 	New() (rsb ResponseBuilder)
-	Header(header Header) (err Error)
+	Header(map[string][]string) (err Error)
 	Write(body []byte) (err Error)
 	Response() *response
 }