diff --git a/packages/minmo.el b/packages/minmo.el
index 273a1ea..3283b8c 100644
--- a/packages/minmo.el
+++ b/packages/minmo.el
@@ -114,7 +114,7 @@ filesystem FSTYPE, 'git or 'disk."
   (or minmo--git-status-cache " "))
 
 (defvar minmo--git-directory-table (make-hash-table :test 'equal)
-  "Store known directories with .git")
+  "Store known directories with and without a ruling .git")
 
 (defun minmo--find-git (file &optional force)
   "Walk up the directory tree looking for `.git'. Returns the path or nil.
@@ -122,8 +122,9 @@ Optional FORCE means ignore the minmo--git-directory-table."
   (let* ((dir (file-name-directory file))
          (hash (gethash dir minmo--git-directory-table)))
     (if (or force (not hash))
-        ;; NOTE: store 'ignore for files not under .git
+        ;; NOTE: store 'ignore for files not under .git, so these calls are also optimized:
         (puthash dir (or (locate-dominating-file file ".git") 'ignore) minmo--git-directory-table)
+      ;; but return nil when 'ignore, so that this function serves as a guard:
       (if (eq hash 'ignore) nil hash))))
 
 (defun minmo--file-exists-locally-p ()