diff --git a/internal/git/git-http.go b/internal/git/git-http.go
index 21b9a808d5631c04d3424ad263de1a82d4e900fe..c50478305c592f8eed8a9a6fd2d8e401f31b405b 100644
--- a/internal/git/git-http.go
+++ b/internal/git/git-http.go
@@ -39,6 +39,8 @@ func postRPCHandler(a *api.API, name string, handler func(*GitHttpResponseWriter
 		}()
 
 		if err := handler(w, r, ar); err != nil {
+			// If the handler already wrote a response this WriteHeader call is a
+			// (harmless) no-op.
 			w.WriteHeader(500)
 			helper.LogError(r, fmt.Errorf("%s: %v", name, err))
 		}