diff --git a/guix/git.scm b/guix/git.scm
index ebe2600209..ed3fa56bc8 100644
--- a/guix/git.scm
+++ b/guix/git.scm
@@ -405,7 +405,16 @@ (define cached-checkout-expiration
 
   ;; Use the mtime rather than the atime to cope with file systems mounted
   ;; with 'noatime'.
-  (file-expiration-time (* 90 24 3600) stat:mtime))
+  (let ((ttl (* 90 24 3600))
+        (max-checkout-retention (* 9 30 24 3600)))
+    (lambda (file)
+      (match (false-if-exception (lstat file))
+        (#f 0)                     ;FILE may have been deleted in the meantime
+        (st (min (pk 'ttl (+ (stat:mtime st) ttl))
+                 (pk 'maxttl (match (false-if-exception
+                          (lstat (in-vicinity file ".git/config")))
+                    (#f +inf.0)
+                    (st (+ (stat:mtime st) max-checkout-retention))))))))))
 
 (define %checkout-cache-cleanup-period
   ;; Period for the removal of expired cached checkouts.