diff --git a/CHANGELOG b/CHANGELOG
index 844a0d1b0c..5f1284a71c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Add history on payment term line delta
+
 Version 5.0.0 - 2018-10-01
 * Bug fixes (see mercurial logs for details)
 * Remove support for Python 2.7
diff --git a/__init__.py b/__init__.py
index 5da4c27629..1f54d851e5 100644
--- a/__init__.py
+++ b/__init__.py
@@ -2,16 +2,17 @@
 # this repository contains the full copyright notices and license terms.
 
 from trytond.pool import Pool
-from .party import *
-from .payment_term import *
-from .invoice import *
+from . import party
+from . import account
+from . import account_invoice
 
 
 def register():
     Pool.register(
-        Party,
-        Address,
-        PaymentTerm,
-        PaymentTermLine,
-        Invoice,
+        party.Party,
+        party.Address,
+        account.Invoice,
+        account_invoice.PaymentTerm,
+        account_invoice.PaymentTermLine,
+        account_invoice.PaymentTermLineRelativeDelta,
         module='account_invoice_history', type_='model')
diff --git a/invoice.py b/account.py
similarity index 100%
rename from invoice.py
rename to account.py
diff --git a/payment_term.py b/account_invoice.py
similarity index 75%
rename from payment_term.py
rename to account_invoice.py
index b2d3200be2..b028ba2956 100644
--- a/payment_term.py
+++ b/account_invoice.py
@@ -2,8 +2,6 @@
 # this repository contains the full copyright notices and license terms.
 from trytond.pool import PoolMeta
 
-__all__ = ['PaymentTerm', 'PaymentTermLine']
-
 
 class PaymentTerm(metaclass=PoolMeta):
     __name__ = 'account.invoice.payment_term'
@@ -13,3 +11,8 @@ class PaymentTerm(metaclass=PoolMeta):
 class PaymentTermLine(metaclass=PoolMeta):
     __name__ = 'account.invoice.payment_term.line'
     _history = True
+
+
+class PaymentTermLineRelativeDelta(metaclass=PoolMeta):
+    __name__ = 'account.invoice.payment_term.line.delta'
+    _history = True