diff --git a/trytond/CHANGELOG b/trytond/CHANGELOG
index b4223c0d4c..425ac608e1 100644
--- a/trytond/CHANGELOG
+++ b/trytond/CHANGELOG
@@ -1,3 +1,4 @@
+* Set Decimal precision of default context from TRYTOND_DECIMAL_PREC
 * Replace usage of docstring of Model by __string__ attribute
 * Rename ir.model.field 'field_description' into 'string'
 * Replace docstring of models by __string__
diff --git a/trytond/trytond/__init__.py b/trytond/trytond/__init__.py
index 2153bfeb82..71e2ef3dee 100644
--- a/trytond/trytond/__init__.py
+++ b/trytond/trytond/__init__.py
@@ -1,5 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
+
+import decimal
 import os
 import time
 import warnings
@@ -40,3 +42,5 @@ def default_user_agent(name="Tryton"):
 
 if requests_utils:
     requests_utils.default_user_agent = default_user_agent
+
+decimal.DefaultContext.prec = int(os.environ.get('TRYTOND_DECIMAL_PREC', 28))
diff --git a/trytond/trytond/commandline.py b/trytond/trytond/commandline.py
index f273b9fbbe..99b4d556a5 100644
--- a/trytond/trytond/commandline.py
+++ b/trytond/trytond/commandline.py
@@ -65,6 +65,9 @@ def get_parser():
     parser.add_argument(
         "--logconf", dest="logconf", default=logging_config, metavar='FILE',
         help="set logging configuration file (ConfigParser format)")
+    parser.epilog = (
+        "The default Decimal precision can be specified in the "
+        "TRYTOND_DECIMAL_PREC environment variable.")
 
     return parser