diff --git a/site-lisp/db-utils.el b/site-lisp/db-utils.el
index 1dbe173..d5431ad 100644
--- a/site-lisp/db-utils.el
+++ b/site-lisp/db-utils.el
@@ -210,6 +210,9 @@ If not given, FORMAT-STRING defaults to some ISO 8601-like format."
   (let* ((high-seconds (- high 2208992400)) ; subtract seconds between 1900-01-01 and the epoch
          (h (lsh high-seconds -16))
   (let* ((high-seconds (- high 2208988800)) ; subtract seconds between 1900-01-01 and the epoch
+         (h (if (< high-seconds 0)
+                (- (lsh (- high-seconds) -16))
+              (lsh high-seconds -16)))
          (l (% high-seconds 65536))
          (u (floor (* (/ low 4294967296.0) 1e6)))
          (p (- low (floor (/ (* u 4294967296) 1e6)))))