diff --git a/taiga/userstorage/api.py b/taiga/userstorage/api.py
index 62575d2b..5b097e71 100644
--- a/taiga/userstorage/api.py
+++ b/taiga/userstorage/api.py
@@ -17,14 +17,15 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from django.utils.translation import ugettext as _
-from django.db import IntegrityError
 
 from taiga.base.api import ModelCrudViewSet
+from taiga.base.api.serializers import ValidationError
 from taiga.base import exceptions as exc
 
 from . import models
 from . import filters
 from . import serializers
+from . import validators
 from . import permissions
 
 
@@ -32,6 +33,7 @@ class StorageEntriesViewSet(ModelCrudViewSet):
     model = models.StorageEntry
     filter_backends = (filters.StorageEntriesFilterBackend,)
     serializer_class = serializers.StorageEntrySerializer
+    validator_class = validators.StorageEntryValidator
     permission_classes = [permissions.StorageEntriesPermission]
     lookup_field = "key"
 
@@ -45,9 +47,11 @@ class StorageEntriesViewSet(ModelCrudViewSet):
             obj.owner = self.request.user
 
     def create(self, *args, **kwargs):
-        try:
-            return super().create(*args, **kwargs)
-        except IntegrityError:
-            key = self.request.DATA.get("key", None)
-            raise exc.IntegrityError(_("Duplicate key value violates unique constraint. "
-                                       "Key '{}' already exists.").format(key))
+        key = self.request.DATA.get("key", None)
+        if (key and self.request.user.is_authenticated() and
+                self.request.user.storage_entries.filter(key=key).exists()):
+            raise exc.BadRequest(
+                _("Duplicate key value violates unique constraint. "
+                  "Key '{}' already exists.").format(key)
+            )
+        return super().create(*args, **kwargs)
diff --git a/taiga/userstorage/serializers.py b/taiga/userstorage/serializers.py
index 5fd97692..38765f19 100644
--- a/taiga/userstorage/serializers.py
+++ b/taiga/userstorage/serializers.py
@@ -17,15 +17,11 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from taiga.base.api import serializers
-from taiga.base.fields import JsonField
-
-from . import models
+from taiga.base.fields import Field
 
 
-class StorageEntrySerializer(serializers.ModelSerializer):
-    value = JsonField(label="value")
-
-    class Meta:
-        model = models.StorageEntry
-        fields = ("key", "value", "created_date", "modified_date")
-        read_only_fields = ("created_date", "modified_date")
+class StorageEntrySerializer(serializers.LightSerializer):
+    key = Field()
+    value = Field()
+    created_date = Field()
+    modified_date = Field()
diff --git a/taiga/userstorage/validators.py b/taiga/userstorage/validators.py
new file mode 100644
index 00000000..615b88d7
--- /dev/null
+++ b/taiga/userstorage/validators.py
@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# Copyright (C) 2014-2016 Andrey Antukh <niwi@niwi.nz>
+# Copyright (C) 2014-2016 Jesús Espino <jespinog@gmail.com>
+# Copyright (C) 2014-2016 David Barragán <bameda@dbarragan.com>
+# Copyright (C) 2014-2016 Alejandro Alonso <alejandro.alonso@kaleidos.net>
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from taiga.base.api import validators
+
+from . import models
+
+
+class StorageEntryValidator(validators.ModelValidator):
+    class Meta:
+        model = models.StorageEntry
+        fields = ("key", "value")