diff --git a/oml/item/api.py b/oml/item/api.py
index 6385e7f..857dcf9 100644
--- a/oml/item/api.py
+++ b/oml/item/api.py
@@ -146,13 +146,15 @@ def edit(data):
         ids = [ids]
     edited = []
     for id in ids:
-        item = models.Item.get(id)
+        state.db.session.begin(subtransactions=True)
+        item = models.Item.get(id, for_update=True)
         if item and item.json().get('mediastate') == 'available':
             item.edit(data)
             response = item.json()
             edited.append(id)
         else:
             logger.info('can only edit available items %s', id)
+        state.db.session.commit()
     if len(ids) > 1:
         response = data
         response['id'] = edited
diff --git a/oml/item/models.py b/oml/item/models.py
index f936838..b2d5c3a 100644
--- a/oml/item/models.py
+++ b/oml/item/models.py
@@ -75,10 +75,13 @@ class Item(db.Model):
         self.meta = {}
 
     @classmethod
-    def get(cls, id):
+    def get(cls, id, for_update=False):
         if isinstance(id, list):
             id = base64.b32encode(hashlib.sha1(''.join(id)).digest())
-        return cls.query.filter_by(id=id).first()
+        qs = cls.query.filter_by(id=id)
+        if for_update:
+            qs = qs.with_for_update()
+        return qs.first()
 
     @classmethod
     def get_or_create(cls, id, info=None):
diff --git a/oml/media/pdf.py b/oml/media/pdf.py
index fdf5a01..c4e9719 100644
--- a/oml/media/pdf.py
+++ b/oml/media/pdf.py
@@ -209,7 +209,7 @@ def info(pdf):
     if settings.server['extract_text']:
         text = extract_text(pdf)
         data['textsize'] = len(text)
-        if not 'isbn' in data:
+        if 'isbn' not in data:
             isbn = extract_isbn(text)
             if isbn:
                 data['isbn'] = isbn