diff --git a/guix/tests/git.scm b/guix/tests/git.scm
index 94f1021c79..d51e49e514 100644
--- a/guix/tests/git.scm
+++ b/guix/tests/git.scm
@@ -73,6 +73,7 @@ Return DIRECTORY on success."
          (mkdir-p (dirname file))
          (call-with-output-file file
            (lambda (port)
+             (set-port-encoding! port "UTF-8")
              (display (if (string? contents)
                           contents
                           (with-repository directory repository