1 files changed, 10 insertions, 0 deletions

diff --git a/test/src/editfns-tests.el b/test/src/editfns-tests.el
index 487f3aaa666..4a840c8d7d1 100644
--- a/test/src/editfns-tests.el
+++ b/test/src/editfns-tests.el
@@ -253,6 +253,16 @@
            (format-time-string "%Y-%m-%d %H:%M:%S.%3N %z" nil
                                (concat (make-string 2048 ?X) "0")))))
 
+(defun editfns-tests--have-leap-seconds ()
+  (string-equal (format-time-string "%Y-%m-%d %H:%M:%S" 78796800 t)
+                "1972-06-30 23:59:60"))
+
+(ert-deftest format-time-string-with-bignum-on-32-bit ()
+  (should (or (string-equal
+               (format-time-string "%Y-%m-%d %H:%M:%S" (- (ash 1 31) 3600) t)
+               "2038-01-19 02:14:08")
+              (editfns-tests--have-leap-seconds))))
+
 (ert-deftest format-with-field ()
   (should (equal (format "First argument %2$s, then %3$s, then %1$s" 1 2 3)
                  "First argument 2, then 3, then 1"))