diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index 54ea69f7f1..0a13ec8492 100644
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -2280,6 +2280,9 @@ DecodeTimeOnly(char **field, int *ftype, int nf,
 			GetCurrentDateTime(tmp);
 		else
 		{
+			/* a date has to be fully specified */
+			if ((fmask & DTK_DATE_M) != DTK_DATE_M)
+				return DTERR_BAD_FORMAT;
 			tmp->tm_year = tm->tm_year;
 			tmp->tm_mon = tm->tm_mon;
 			tmp->tm_mday = tm->tm_mday;
@@ -2307,6 +2310,9 @@ DecodeTimeOnly(char **field, int *ftype, int nf,
 			GetCurrentDateTime(tmp);
 		else
 		{
+			/* a date has to be fully specified */
+			if ((fmask & DTK_DATE_M) != DTK_DATE_M)
+				return DTERR_BAD_FORMAT;
 			tmp->tm_year = tm->tm_year;
 			tmp->tm_mon = tm->tm_mon;
 			tmp->tm_mday = tm->tm_mday;