diff --git a/addons/account/account_analytic_line.py b/addons/account/account_analytic_line.py
index fa150b291dc..a93dc70b2fb 100644
--- a/addons/account/account_analytic_line.py
+++ b/addons/account/account_analytic_line.py
@@ -80,7 +80,10 @@ class account_analytic_line(osv.osv):
         j_id = analytic_journal_obj.browse(cr, uid, journal_id, context=context)
         prod = product_obj.browse(cr, uid, prod_id, context=context)
         result = 0.0
-
+        if prod_id:
+            unit = prod.uom_id.id
+            if j_id.type == 'purchase':
+                unit = prod.uom_po_id.id
         if j_id.type <> 'sale':
             a = prod.product_tmpl_id.property_account_expense.id
             if not a:
@@ -127,6 +130,7 @@ class account_analytic_line(osv.osv):
         return {'value': {
             'amount': result,
             'general_account_id': a,
+            'product_uom_id': unit
             }
         }
 
@@ -155,4 +159,4 @@ class res_partner(osv.osv):
 
 res_partner()
 
-# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
\ No newline at end of file
+# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: