diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index ed03c50a6d..7177c1a62f 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -5992,12 +5992,19 @@ interval_part_common(PG_FUNCTION_ARGS, bool retnumeric)
 				intresult = tm->tm_mday;
 				break;
 
+			case DTK_WEEK:
+				intresult = tm->tm_mday / 7;
+				break;
+
 			case DTK_MONTH:
 				intresult = tm->tm_mon;
 				break;
 
 			case DTK_QUARTER:
-				intresult = (tm->tm_mon / 3) + 1;
+				if (tm->tm_year >= 0)
+					intresult = (tm->tm_mon / 3) + 1;
+				else
+					intresult = -((-tm->tm_mon / 3) + 1);
 				break;
 
 			case DTK_YEAR: