diff --git a/db/ddlutils/postgresql/functions/firstOf.sql b/db/ddlutils/postgresql/functions/firstOf.sql
index 88cb564b40..3557964f6e 100644
--- a/db/ddlutils/postgresql/functions/firstOf.sql
+++ b/db/ddlutils/postgresql/functions/firstOf.sql
@@ -31,10 +31,10 @@ $$
 DECLARE
 datepart VARCHAR;
 datetime TIMESTAMP WITH TIME ZONE;
-offset INTEGER;
+offsetdays INTEGER;
 BEGIN
 	datepart = $2;
-	offset = 0;
+	offsetdays = 0;
 	IF $2 IN ('') THEN
 		datepart = 'millennium';
 	ELSEIF $2 IN ('') THEN
@@ -58,7 +58,7 @@ BEGIN
 	ELSEIF $2 IN ('DAY','DY','D') THEN
 		datepart = 'week';
 		-- move to sunday to make it compatible with oracle and SQLJ
-		offset = -1;
+		offsetdays = -1;
 	ELSEIF $2 IN ('HH','HH12','HH24') THEN
 		datepart = 'hour';
 	ELSEIF $2 IN ('MI') THEN
@@ -71,6 +71,6 @@ BEGIN
 		datepart = 'microseconds';
 	END IF;
 	datetime = date_trunc(datepart, $1); 
-RETURN cast(datetime as date) + offset;
+RETURN cast(datetime as date) + offsetdays;
 END;
 $$ LANGUAGE plpgsql;
diff --git a/migration/360lts-release/oracle/794_791_BF3214377_FixFirstOf.sql b/migration/360lts-release/oracle/794_791_BF3214377_FixFirstOf.sql
new file mode 100644
index 0000000000..1e28f999f9
--- /dev/null
+++ b/migration/360lts-release/oracle/794_791_BF3214377_FixFirstOf.sql
@@ -0,0 +1 @@
+-- Fix firstOf fo PostgreSQL 9
\ No newline at end of file
diff --git a/migration/360lts-release/postgresql/794_791_BF3214377_FixFirstOf.sql b/migration/360lts-release/postgresql/794_791_BF3214377_FixFirstOf.sql
new file mode 100644
index 0000000000..3557964f6e
--- /dev/null
+++ b/migration/360lts-release/postgresql/794_791_BF3214377_FixFirstOf.sql
@@ -0,0 +1,76 @@
+/*
+*This file is part of Adempiere ERP Bazaar
+*http://www.adempiere.org
+*
+*Copyright (C) 2006 Gavin Dunse
+*Copyright (C) 1999-2006 ComPiere, inc
+*
+*This program is free software; you can redistribute it and/or
+*modify it under the terms of the GNU General Public License
+*as published by the Free Software Foundation; either version 2
+*of the License, or (at your option) any later version.
+*
+*This program is distributed in the hope that it will be useful,
+*but WITHOUT ANY WARRANTY; without even the implied warranty of
+*MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+*GNU General Public License for more details.
+*
+*You should have received a copy of the GNU General Public License
+*along with this program; if not, write to the Free Software
+*Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.of
+*/
+
+/** Get Character at Position */
+SET search_path = adempiere, pg_catalog;
+
+CREATE OR REPLACE FUNCTION firstOf (
+IN TIMESTAMP WITH TIME ZONE, -- $1 date
+IN VARCHAR -- $2 part of date
+) RETURNS DATE AS
+$$
+DECLARE
+datepart VARCHAR;
+datetime TIMESTAMP WITH TIME ZONE;
+offsetdays INTEGER;
+BEGIN
+	datepart = $2;
+	offsetdays = 0;
+	IF $2 IN ('') THEN
+		datepart = 'millennium';
+	ELSEIF $2 IN ('') THEN
+		datepart = 'century';
+	ELSEIF $2 IN ('') THEN
+		datepart = 'decade';
+	ELSEIF $2 IN ('IYYY','IY','I') THEN
+		datepart = 'year';
+	ELSEIF $2 IN ('SYYYY','YYYY','YEAR','SYEAR','YYY','YY','Y') THEN
+		datepart = 'year';
+	ELSEIF $2 IN ('Q') THEN
+		datepart = 'quarter';
+	ELSEIF $2 IN ('MONTH','MON','MM','RM') THEN
+		datepart = 'month';
+	ELSEIF $2 IN ('IW') THEN
+		datepart = 'week';
+	ELSEIF $2 IN ('W') THEN
+		datepart = 'week';
+	ELSEIF $2 IN ('DDD','DD','J') THEN
+		datepart = 'day';
+	ELSEIF $2 IN ('DAY','DY','D') THEN
+		datepart = 'week';
+		-- move to sunday to make it compatible with oracle and SQLJ
+		offsetdays = -1;
+	ELSEIF $2 IN ('HH','HH12','HH24') THEN
+		datepart = 'hour';
+	ELSEIF $2 IN ('MI') THEN
+		datepart = 'minute';
+	ELSEIF $2 IN ('') THEN
+		datepart = 'second';
+	ELSEIF $2 IN ('') THEN
+		datepart = 'milliseconds';
+	ELSEIF $2 IN ('') THEN
+		datepart = 'microseconds';
+	END IF;
+	datetime = date_trunc(datepart, $1); 
+RETURN cast(datetime as date) + offsetdays;
+END;
+$$ LANGUAGE plpgsql;