diff --git a/caddyhttp/header/header.go b/caddyhttp/header/header.go
index 7207c52e6..28f95d45f 100644
--- a/caddyhttp/header/header.go
+++ b/caddyhttp/header/header.go
@@ -115,3 +115,23 @@ func (rww *responseWriterWrapper) Hijack() (net.Conn, *bufio.ReadWriter, error)
 	}
 	return nil, nil, httpserver.NonHijackerError{Underlying: rww.w}
 }
+
+// Flush implements http.Flusher. It simply wraps the underlying
+// ResponseWriter's Flush method if there is one, or panics.
+func (rww *responseWriterWrapper) Flush() {
+	if f, ok := rww.w.(http.Flusher); ok {
+		f.Flush()
+	} else {
+		panic(httpserver.NonFlusherError{Underlying: rww.w}) // should be recovered at the beginning of middleware stack
+	}
+}
+
+// CloseNotify implements http.CloseNotifier.
+// It just inherits the underlying ResponseWriter's CloseNotify method.
+// It panics if the underlying ResponseWriter is not a CloseNotifier.
+func (rww *responseWriterWrapper) CloseNotify() <-chan bool {
+	if cn, ok := rww.w.(http.CloseNotifier); ok {
+		return cn.CloseNotify()
+	}
+	panic(httpserver.NonCloseNotifierError{Underlying: rww.w})
+}