diff --git a/module/mes/guile.mes b/module/mes/guile.mes
index a131bbae..ffec0b54 100644
--- a/module/mes/guile.mes
+++ b/module/mes/guile.mes
@@ -149,3 +149,8 @@
                               (set! set-current-input-port save-set-current-input-port)
                               string-port)))))))
       string-port)))
+
+(define (dirname file-name)
+  (let ((lst (filter (negate string-null?) (string-split file-name #\/))))
+    (if (<= (length lst) 1) "."
+        (string-join (list-head lst (1- (length lst))) "/"))))