diff --git a/collects/tests/srfi/19/tests.ss b/collects/tests/srfi/19/tests.ss
index c12248d6bf..977f9ed70e 100644
--- a/collects/tests/srfi/19/tests.ss
+++ b/collects/tests/srfi/19/tests.ss
@@ -4,6 +4,7 @@
 ;;   John Clements                             -- 2004-08-16
 ;;   Dave Gurnell (string->date, date->string) -- 2007-09-14 
 ;;   Dave Gurnell (time{=,<,>,<=,>=}?)         -- 2009-11-26
+;;   John Clements (nanoseconds off by x100)   -- 2009-12-15
 
 (require srfi/19/time)
 
@@ -187,10 +188,22 @@
       (check = 365 (- (date->modified-julian-day (srfi:make-date 0 0 0 0 1 1 2004 0))
                       (date->modified-julian-day (srfi:make-date 0 0 0 0 1 1 2003 0))))
       (let ([test-date (srfi:make-date 0 0 0 0 1 1 2003 -7200)])
-        (check tm:date= test-date (modified-julian-day->date (date->modified-julian-day test-date) -7200))))))
+        (check tm:date= test-date (modified-julian-day->date (date->modified-julian-day test-date) -7200))))
+    
+    ;; nanosecnds off by a factor of 100...
+    (test-case "nanosecond order-of-magnitude"
+               ;; half a second should be within 1/10th of 10^9 / 2 nanoseconds (currently off by a factor of 100)
+               (check-within (let ([t (date-nanosecond (current-date))])
+                               (sleep 0.5)
+                               (abs (- (date-nanosecond (current-date)) t)))
+                             (* 1/2  (expt 10 9))
+                             (* 1/10 (expt 10 9))))))
 
 ; Helper checks and procedures -----------------
 
+(define-simple-check (check-within actual expected epsilon)
+    (< (abs (- actual expected)) epsilon))
+
 (define-check (check-one-utc-tai-edge utc tai-diff tai-last-diff)
   (let* (;; right on the edge they should be the same
          (utc-basic (make-time 'time-utc 0 utc))