diff --git a/CHANGES b/CHANGES
index a3c403c741..46d5009ce7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+
+ 472.	[bug]		Off-by-one error caused isc_time_add() to sometimes
+			produce invalid time values.
+
  471.	[bug]		nsupdate didn't compile on HP/UX 10.20
 
  470.	[feature]	$GENERATE is now supported.  See also
diff --git a/lib/isc/unix/time.c b/lib/isc/unix/time.c
index f6dc61e0bb..add0e94cf4 100644
--- a/lib/isc/unix/time.c
+++ b/lib/isc/unix/time.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: time.c,v 1.28 2000/08/01 01:31:30 tale Exp $ */
+/* $Id: time.c,v 1.29 2000/09/18 18:43:03 gson Exp $ */
 
 #include <config.h>
 
@@ -257,7 +257,7 @@ isc_time_add(isc_time_t *t, isc_interval_t *i, isc_time_t *result) {
 
 	result->seconds = t->seconds + i->seconds;
 	result->nanoseconds = t->nanoseconds + i->nanoseconds;
-	if (result->nanoseconds > NS_PER_S) {
+	if (result->nanoseconds >= NS_PER_S) {
 		result->seconds++;
 		result->nanoseconds -= NS_PER_S;
 	}