diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index cb57d8182fe..5e929b0f175 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.118.2.12 2009/05/01 19:29:42 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.118.2.13 2009/08/18 21:23:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3093,6 +3093,9 @@ DecodeInterval(char **field, int *ftype, int nf, int *dtype, struct tm * tm, fse
 						break;
 
 					case DTK_MILLISEC:
+						/* avoid overflowing the fsec field */
+						tm->tm_sec += val / 1000;
+						val -= (val / 1000) * 1000;
 #ifdef HAVE_INT64_TIMESTAMP
 						*fsec += ((val + fval) * 1000);
 #else