diff --git a/addons/stock/wizard/stock_partial_picking.py b/addons/stock/wizard/stock_partial_picking.py
index dd91f20e8cf..7edeb694510 100644
--- a/addons/stock/wizard/stock_partial_picking.py
+++ b/addons/stock/wizard/stock_partial_picking.py
@@ -96,8 +96,11 @@ class stock_partial_picking(osv.osv_memory):
 
     def default_get(self, cr, uid, fields, context=None):
         if context is None: context = {}
-        res = super(stock_partial_picking, self).default_get(cr, uid, fields, context=context)
         picking_ids = context.get('active_ids', [])
+        if context['active_model'] == 'purchase.order':
+            for purchase_order in self.pool.get('purchase.order').browse(cr, uid, picking_ids, context=context):
+                picking_ids = [picking.id for picking in purchase_order.picking_ids]
+        res = super(stock_partial_picking, self).default_get(cr, uid, fields, context=context)
         if not picking_ids or len(picking_ids) != 1:
             # Partial Picking Processing may only be done for one picking at a time
             return res
@@ -105,7 +108,7 @@ class stock_partial_picking(osv.osv_memory):
         # (already seen in previous bug where context passed was containing ir.ui.menu as active_model and the menu 
         # ID as active_id). Though this should be fixed in clients now, this place is sensitive enough to ensure the
         # consistancy of the context.
-        assert context.get('active_model') in ('stock.picking', 'stock.picking.in', 'stock.picking.out'), 'Bad context propagation'
+        assert context.get('active_model') in ('stock.picking', 'stock.picking.in', 'stock.picking.out', 'purchase.order'), 'Bad context propagation'
         picking_id, = picking_ids
         if 'picking_id' in fields:
             res.update(picking_id=picking_id)