diff --git a/src/interfaces/ecpg/pgtypeslib/dt_common.c b/src/interfaces/ecpg/pgtypeslib/dt_common.c
index 99bdc94d6d..97800a51c8 100644
--- a/src/interfaces/ecpg/pgtypeslib/dt_common.c
+++ b/src/interfaces/ecpg/pgtypeslib/dt_common.c
@@ -1530,7 +1530,8 @@ DecodeTimezone(char *str, int *tzp)
 	if (*str == '-')
 		tz = -tz;
 
-	*tzp = -tz;
+	if (tzp != NULL)
+		*tzp = -tz;
 	return *cp != '\0';
 }								/* DecodeTimezone() */
 
@@ -1566,7 +1567,8 @@ DecodePosixTimezone(char *str, int *tzp)
 	{
 		case DTZ:
 		case TZ:
-			*tzp = -(val + tz);
+			if (tzp != NULL)
+				*tzp = -(val + tz);
 			break;
 
 		default:
@@ -1790,8 +1792,6 @@ DecodeDateTime(char **field, int *ftype, int nf,
 	bool		haveTextMonth = false;
 	bool		is2digits = false;
 	bool		bc = false;
-	int			t = 0;
-	int		   *tzp = &t;
 
 	/***
 	 * We'll insist on at least all of the date fields, but initialize the
@@ -1804,8 +1804,6 @@ DecodeDateTime(char **field, int *ftype, int nf,
 	*fsec = 0;
 	/* don't know daylight savings time status apriori */
 	tm->tm_isdst = -1;
-	if (tzp != NULL)
-		*tzp = 0;
 
 	for (i = 0; i < nf; i++)
 	{
@@ -1822,16 +1820,13 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					char	   *cp;
 					int			jday;
 
-					if (tzp == NULL)
-						return -1;
-
 					jday = strtoint(field[i], &cp, 10);
 					if (*cp != '-')
 						return -1;
 
 					j2date(jday, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
 					/* Get the time zone from the end of the string */
-					if (DecodeTimezone(cp, tzp) != 0)
+					if (DecodeTimezone(cp, NULL) != 0)
 						return -1;
 
 					tmask = DTK_DATE_M | DTK_TIME_M | DTK_M(TZ);
@@ -1847,10 +1842,6 @@ DecodeDateTime(char **field, int *ftype, int nf,
 				else if (((fmask & DTK_DATE_M) == DTK_DATE_M)
 						 || (ptype != 0))
 				{
-					/* No time zone accepted? Then quit... */
-					if (tzp == NULL)
-						return -1;
-
 					if (isdigit((unsigned char) *field[i]) || ptype != 0)
 					{
 						char	   *cp;
@@ -1875,7 +1866,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 							return -1;
 
 						/* Get the time zone from the end of the string */
-						if (DecodeTimezone(cp, tzp) != 0)
+						if (DecodeTimezone(cp, NULL) != 0)
 							return -1;
 						*cp = '\0';
 
@@ -1895,7 +1886,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					}
 					else
 					{
-						if (DecodePosixTimezone(field[i], tzp) != 0)
+						if (DecodePosixTimezone(field[i], NULL) != 0)
 							return -1;
 
 						ftype[i] = DTK_TZ;
@@ -1922,12 +1913,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 
 			case DTK_TZ:
 				{
-					int			tz;
-
-					if (tzp == NULL)
-						return -1;
-
-					if (DecodeTimezone(field[i], &tz) != 0)
+					if (DecodeTimezone(field[i], NULL) != 0)
 						return -1;
 
 					/*
@@ -1937,15 +1923,9 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					if (i > 0 && (fmask & DTK_M(TZ)) != 0 &&
 						ftype[i - 1] == DTK_TZ &&
 						isalpha((unsigned char) *field[i - 1]))
-					{
-						*tzp -= tz;
 						tmask = 0;
-					}
 					else
-					{
-						*tzp = tz;
 						tmask = DTK_M(TZ);
-					}
 				}
 				break;
 
@@ -2037,7 +2017,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 
 						case DTK_TZ:
 							tmask = DTK_M(TZ);
-							if (DecodeTimezone(field[i], tzp) != 0)
+							if (DecodeTimezone(field[i], NULL) != 0)
 								return -1;
 							break;
 
@@ -2173,8 +2153,6 @@ DecodeDateTime(char **field, int *ftype, int nf,
 								tm->tm_hour = 0;
 								tm->tm_min = 0;
 								tm->tm_sec = 0;
-								if (tzp != NULL)
-									*tzp = 0;
 								break;
 
 							default:
@@ -2207,9 +2185,6 @@ DecodeDateTime(char **field, int *ftype, int nf,
 						 */
 						tmask |= DTK_M(DTZ);
 						tm->tm_isdst = 1;
-						if (tzp == NULL)
-							return -1;
-						*tzp -= val;
 						break;
 
 					case DTZ:
@@ -2220,17 +2195,11 @@ DecodeDateTime(char **field, int *ftype, int nf,
 						 */
 						tmask |= DTK_M(TZ);
 						tm->tm_isdst = 1;
-						if (tzp == NULL)
-							return -1;
-						*tzp = -val;
 						ftype[i] = DTK_TZ;
 						break;
 
 					case TZ:
 						tm->tm_isdst = 0;
-						if (tzp == NULL)
-							return -1;
-						*tzp = -val;
 						ftype[i] = DTK_TZ;
 						break;
 
@@ -2336,7 +2305,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 		 * result afterwards anyway so we only check for this error: daylight
 		 * savings time modifier but no standard timezone?
 		 */
-		if ((fmask & DTK_DATE_M) == DTK_DATE_M && tzp != NULL && !(fmask & DTK_M(TZ)) && (fmask & DTK_M(DTZMOD)))
+		if ((fmask & DTK_DATE_M) == DTK_DATE_M && !(fmask & DTK_M(TZ)) && (fmask & DTK_M(DTZMOD)))
 			return -1;
 	}