internal/testutil/status_writer.go | 2 ++

diff --git a/internal/testutil/status_writer.go b/internal/testutil/status_writer.go
index ac872d57c04725556e1b4e758aa27a09dcddbb52..bcc5c2b5d6b00ebc4f40c34514f94bd50d24cba9 100644
--- a/internal/testutil/status_writer.go
+++ b/internal/testutil/status_writer.go
@@ -40,7 +40,9 @@ 	}
 	http.HandleFunc(
 		pattern,
 		func(w http.ResponseWriter, r *http.Request) {
+			mu.Lock()
 			sw := sws[pattern]
+			mu.Unlock()
 			if sw == nil {
 				http.NotFound(w, r)
 				return