diff --git a/exceptions.py b/exceptions.py
new file mode 100644
index 0000000000..ef503d5730
--- /dev/null
+++ b/exceptions.py
@@ -0,0 +1,12 @@
+# This file is part of Tryton.  The COPYRIGHT file at the top level of
+# this repository contains the full copyright notices and license terms.
+
+from trytond.model.exceptions import ValidationError
+
+
+class CompanyValidationError(ValidationError):
+    pass
+
+
+class DurationValidationError(ValidationError):
+    pass
diff --git a/line.py b/line.py
index b3cfe17429..6e8c39fab4 100644
--- a/line.py
+++ b/line.py
@@ -7,12 +7,15 @@ from sql import Literal
 from sql.aggregate import Max, Sum
 from sql.functions import Extract, CharLength
 
+from trytond.i18n import gettext
 from trytond.model import ModelView, ModelSQL, fields, Unique
 from trytond.wizard import Wizard, StateView, StateAction, Button
 from trytond.pyson import Eval, PYSONEncoder, Date
 from trytond.transaction import Transaction
 from trytond.pool import Pool
 
+from .exceptions import DurationValidationError
+
 __all__ = ['Line', 'EnterLinesStart', 'EnterLines',
     'HoursEmployee', 'HoursEmployeeContext',
     'HoursEmployeeWeekly', 'HoursEmployeeMonthly']
@@ -64,13 +67,9 @@ class Line(ModelSQL, ModelView):
         t = cls.__table__()
         cls._sql_constraints = [
             ('uuid_unique', Unique(t, t.uuid),
-                "The UUID of timesheet line must be unique."),
+                'timesheet.msg_line_uuid_unique'),
             ]
         cls._order.insert(0, ('date', 'DESC'))
-        cls._error_messages.update({
-                'duration_positive': (
-                    'Duration of line "%(line)s" must be positive.'),
-                })
 
     @classmethod
     def __register__(cls, module_name):
@@ -134,9 +133,9 @@ class Line(ModelSQL, ModelView):
 
     def check_duration(self):
         if self.duration < datetime.timedelta():
-            self.raise_user_error('duration_positive', {
-                    'line': self.rec_name,
-                    })
+            raise DurationValidationError(
+                gettext('timesheet.msg_line_duration_positive',
+                    line=self.rec_name))
 
     @property
     def hours(self):
diff --git a/message.xml b/message.xml
new file mode 100644
index 0000000000..49459b83ab
--- /dev/null
+++ b/message.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
+this repository contains the full copyright notices and license terms. -->
+<tryton>
+    <data group="1">
+        <record model="ir.message" id="msg_work_company_different_origin">
+            <field name="text">The companies associated with work "%(work)s" and its origin differ.</field>
+        </record>
+        <record model="ir.message" id="msg_line_duration_positive">
+            <field name="text">The duration of line "%(line)s" must be positive.</field>
+        </record>
+        <record model="ir.message" id="msg_work_origin_unique_company">
+            <field name="text">Work origin must be unique by company.</field>
+        </record>
+        <record model="ir.message" id="msg_line_uuid_unique">
+            <field name="text">The UUID of timesheet line must be unique.</field>
+        </record>
+    </data>
+</tryton>
diff --git a/tryton.cfg b/tryton.cfg
index 922b0026a0..0b160bdcfe 100644
--- a/tryton.cfg
+++ b/tryton.cfg
@@ -9,3 +9,4 @@ xml:
     timesheet.xml
     work.xml
     line.xml
+    message.xml
diff --git a/work.py b/work.py
index 11192ee7ca..c87935d485 100644
--- a/work.py
+++ b/work.py
@@ -6,12 +6,15 @@ import datetime
 from sql import Literal
 from sql.aggregate import Sum
 
+from trytond.i18n import gettext
 from trytond.model import ModelView, ModelSQL, DeactivableMixin, fields, Unique
 from trytond.pyson import Not, Bool, Eval, If
 from trytond.transaction import Transaction
 from trytond.pool import Pool
 from trytond.tools import reduce_ids, grouped_slice
 
+from .exceptions import CompanyValidationError
+
 __all__ = ['Work', 'WorkContext']
 
 
@@ -70,12 +73,8 @@ class Work(DeactivableMixin, ModelSQL, ModelView):
         t = cls.__table__()
         cls._sql_constraints += [
             ('origin_unique', Unique(t, t.origin, t.company),
-                'The origin must be unique per company.'),
+                'timesheet.msg_work_origin_unique_company'),
             ]
-        cls._error_messages.update({
-                'mismatch_company': ('The company of the work "%(work)s" '
-                    'is different than the origin\'s company'),
-                })
 
     @classmethod
     def __register__(cls, module_name):
@@ -204,9 +203,9 @@ class Work(DeactivableMixin, ModelSQL, ModelView):
         super(Work, cls).validate(works)
         for work in works:
             if work.origin and not work._validate_company():
-                cls.raise_user_error('mismatch_company', {
-                        'work': work.rec_name,
-                        })
+                raise CompanyValidationError(
+                    gettext('timesheet.msg_work_company_different_origin',
+                        work=work.rec_name))
 
     def _validate_company(self):
         return True