diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
new file mode 100644
index 6bf4cf6..b7d7d80
*** a/doc/src/sgml/datatype.sgml
--- b/doc/src/sgml/datatype.sgml
*************** SELECT E'\\xDEADBEEF';
*** 1587,1593 ****
         </row>
         <row>
          <entry><type>interval [ <replaceable>fields</replaceable> ] [ (<replaceable>p</replaceable>) ]</type></entry>
!         <entry>12 bytes</entry>
          <entry>time interval</entry>
          <entry>-178000000 years</entry>
          <entry>178000000 years</entry>
--- 1587,1593 ----
         </row>
         <row>
          <entry><type>interval [ <replaceable>fields</replaceable> ] [ (<replaceable>p</replaceable>) ]</type></entry>
!         <entry>16 bytes</entry>
          <entry>time interval</entry>
          <entry>-178000000 years</entry>
          <entry>178000000 years</entry>
diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
new file mode 100644
index a61b40e..70284e9
*** a/src/backend/utils/adt/datetime.c
--- b/src/backend/utils/adt/datetime.c
*************** DecodeInterval(char **field, int *ftype,
*** 2976,2981 ****
--- 2976,2983 ----
  					type = DTK_MONTH;
  					if (*field[i] == '-')
  						val2 = -val2;
+ 					if (((double)val * MONTHS_PER_YEAR + val2) > INT_MAX)
+ 						return DTERR_FIELD_OVERFLOW;
  					val = val * MONTHS_PER_YEAR + val2;
  					fval = 0;
  				}
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
new file mode 100644
index 4581862..3b8e8e8
*** a/src/backend/utils/adt/timestamp.c
--- b/src/backend/utils/adt/timestamp.c
***************
*** 41,46 ****
--- 41,47 ----
  #error -ffast-math is known to break this code
  #endif
  
+ #define SAMESIGN(a,b)   (((a) < 0) == ((b) < 0))
  
  /* Set at postmaster start */
  TimestampTz PgStartTime;
*************** interval2tm(Interval span, struct pg_tm
*** 1694,1700 ****
  #ifdef HAVE_INT64_TIMESTAMP
  	tfrac = time / USECS_PER_HOUR;
  	time -= tfrac * USECS_PER_HOUR;
! 	tm->tm_hour = tfrac;		/* could overflow ... */
  	tfrac = time / USECS_PER_MINUTE;
  	time -= tfrac * USECS_PER_MINUTE;
  	tm->tm_min = tfrac;
--- 1695,1705 ----
  #ifdef HAVE_INT64_TIMESTAMP
  	tfrac = time / USECS_PER_HOUR;
  	time -= tfrac * USECS_PER_HOUR;
! 	tm->tm_hour = tfrac;
! 	if (!SAMESIGN(tm->tm_hour, tfrac))
! 		ereport(ERROR,
! 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
! 				 errmsg("interval out of range")));
  	tfrac = time / USECS_PER_MINUTE;
  	time -= tfrac * USECS_PER_MINUTE;
  	tm->tm_min = tfrac;
*************** recalc:
*** 1725,1731 ****
  int
  tm2interval(struct pg_tm * tm, fsec_t fsec, Interval *span)
  {
! 	span->month = tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon;
  	span->day = tm->tm_mday;
  #ifdef HAVE_INT64_TIMESTAMP
  	span->time = (((((tm->tm_hour * INT64CONST(60)) +
--- 1730,1740 ----
  int
  tm2interval(struct pg_tm * tm, fsec_t fsec, Interval *span)
  {
! 	double total_months = (double)tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon;
! 
! 	if (total_months > INT_MAX || total_months < INT_MIN)
! 		return -1;
! 	span->month = total_months;
  	span->day = tm->tm_mday;
  #ifdef HAVE_INT64_TIMESTAMP
  	span->time = (((((tm->tm_hour * INT64CONST(60)) +
*************** interval_um(PG_FUNCTION_ARGS)
*** 2826,2833 ****
--- 2835,2855 ----
  	result = (Interval *) palloc(sizeof(Interval));
  
  	result->time = -interval->time;
+ 	/* overflow check copied from int4um */
+ 	if (interval->time != 0 && SAMESIGN(result->time, interval->time))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
  	result->day = -interval->day;
+ 	if (interval->day != 0 && SAMESIGN(result->day, interval->day))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
  	result->month = -interval->month;
+ 	if (interval->month != 0 && SAMESIGN(result->month, interval->month))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
  
  	PG_RETURN_INTERVAL_P(result);
  }
*************** interval_pl(PG_FUNCTION_ARGS)
*** 2872,2879 ****
--- 2894,2919 ----
  	result = (Interval *) palloc(sizeof(Interval));
  
  	result->month = span1->month + span2->month;
+ 	/* overflow check copied from int4pl */
+ 	if (SAMESIGN(span1->month, span2->month) &&
+ 		!SAMESIGN(result->month, span1->month))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
+ 
  	result->day = span1->day + span2->day;
+ 	if (SAMESIGN(span1->day, span2->day) &&
+ 		!SAMESIGN(result->day, span1->day))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
+ 
  	result->time = span1->time + span2->time;
+ 	if (SAMESIGN(span1->time, span2->time) &&
+ 		!SAMESIGN(result->time, span1->time))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
  
  	PG_RETURN_INTERVAL_P(result);
  }
*************** interval_mi(PG_FUNCTION_ARGS)
*** 2888,2895 ****
--- 2928,2954 ----
  	result = (Interval *) palloc(sizeof(Interval));
  
  	result->month = span1->month - span2->month;
+ 	/* overflow check copied from int4mi */
+ 	if (!SAMESIGN(span1->month, span2->month) &&
+ 		!SAMESIGN(result->month, span1->month))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
+ 
  	result->day = span1->day - span2->day;
+ 	if (!SAMESIGN(span1->day, span2->day) &&
+ 		!SAMESIGN(result->day, span1->day))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
+ 
  	result->time = span1->time - span2->time;
+ 	if (!SAMESIGN(span1->time, span2->time) &&
+ 		!SAMESIGN(result->time, span1->time))
+ 		ereport(ERROR,
+ 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+ 				 errmsg("interval out of range")));
+ 
  
  	PG_RETURN_INTERVAL_P(result);
  }
*************** interval_mul(PG_FUNCTION_ARGS)
*** 2906,2920 ****
  	Interval   *span = PG_GETARG_INTERVAL_P(0);
  	float8		factor = PG_GETARG_FLOAT8(1);
  	double		month_remainder_days,
! 				sec_remainder;
  	int32		orig_month = span->month,
  				orig_day = span->day;
  	Interval   *result;
  
  	result = (Interval *) palloc(sizeof(Interval));
  
! 	result->month = (int32) (span->month * factor);
! 	result->day = (int32) (span->day * factor);
  
  	/*
  	 * The above correctly handles the whole-number part of the month and day
--- 2965,2991 ----
  	Interval   *span = PG_GETARG_INTERVAL_P(0);
  	float8		factor = PG_GETARG_FLOAT8(1);
  	double		month_remainder_days,
! 				sec_remainder,
! 				result_double;
  	int32		orig_month = span->month,
  				orig_day = span->day;
  	Interval   *result;
  
  	result = (Interval *) palloc(sizeof(Interval));
  
! 	result_double = span->month * factor;
! 	if (result_double > INT_MAX || result_double < INT_MIN)
! 		ereport(ERROR,
! 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
! 				 errmsg("interval out of range")));
! 	result->month = (int32) result_double;
! 
! 	result_double = span->day * factor;
! 	if (result_double > INT_MAX || result_double < INT_MIN)
! 		ereport(ERROR,
! 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
! 				 errmsg("interval out of range")));
! 	result->day = (int32) result_double;
  
  	/*
  	 * The above correctly handles the whole-number part of the month and day
*************** interval_mul(PG_FUNCTION_ARGS)
*** 2954,2960 ****
  	/* cascade units down */
  	result->day += (int32) month_remainder_days;
  #ifdef HAVE_INT64_TIMESTAMP
! 	result->time = rint(span->time * factor + sec_remainder * USECS_PER_SEC);
  #else
  	result->time = span->time * factor + sec_remainder;
  #endif
--- 3025,3036 ----
  	/* cascade units down */
  	result->day += (int32) month_remainder_days;
  #ifdef HAVE_INT64_TIMESTAMP
! 	result_double = rint(span->time * factor + sec_remainder * USECS_PER_SEC);
! 	if (result_double > INT64_MAX || result_double < INT64_MIN)
! 		ereport(ERROR,
! 				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
! 				 errmsg("interval out of range")));
! 	result->time = (int64) result_double;
  #else
  	result->time = span->time * factor + sec_remainder;
  #endif
diff --git a/src/interfaces/ecpg/pgtypeslib/interval.c b/src/interfaces/ecpg/pgtypeslib/interval.c
new file mode 100644
index efa775d..d603fd4
*** a/src/interfaces/ecpg/pgtypeslib/interval.c
--- b/src/interfaces/ecpg/pgtypeslib/interval.c
*************** recalc:
*** 1036,1041 ****
--- 1036,1043 ----
  static int
  tm2interval(struct tm * tm, fsec_t fsec, interval * span)
  {
+ 	if ((double)tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon > INT_MAX)
+ 		return -1;
  	span->month = tm->tm_year * MONTHS_PER_YEAR + tm->tm_mon;
  #ifdef HAVE_INT64_TIMESTAMP
  	span->time = (((((((tm->tm_mday * INT64CONST(24)) +