diff --git a/beat/web/common/serializers.py b/beat/web/common/serializers.py
index af1d85d3f8dd671e1e41384a5092036d2c455f3b..cd52ad970de0a80311e674cee47c29ffbc2b8a55 100644
--- a/beat/web/common/serializers.py
+++ b/beat/web/common/serializers.py
@@ -25,6 +25,9 @@
 #                                                                             #
 ###############################################################################
 
+import copy
+
+from django.conf import settings
 
 from django.contrib.auth.models import User
 from django.utils import six
@@ -333,20 +336,30 @@ class ContributionCreationSerializer(serializers.ModelSerializer):
             description = description.decode("string_escape")
         return description
 
-    def validate(self, data):
-        user = self.context.get("user")
-        name = self.Meta.model.sanitize_name(data["name"])
-        data["name"] = name
-        version = data.get("version")
+    def validate_declaration(self, declaration):
+        decl = copy.deepcopy(declaration)
+        obj = self.Meta.beat_core_class(prefix=settings.PREFIX, data=decl)
+        if not obj.valid:
+            raise serializers.ValidationError(obj.errors)
+        return declaration
 
+    def validate_version(self, version):
         # If version is not one then it's necessarily a new version
         # forks start at one
-        if version > 1 and "previous_version" not in data:
+        if version > 1 and "previous_version" not in self.initial_data:
+            name = self.initial_data["name"]
             raise serializers.ValidationError(
                 "{} {} version {} incomplete history data posted".format(
                     self.Meta.model.__name__.lower(), name, version
                 )
             )
+        return version
+
+    def validate(self, data):
+        user = self.context.get("user")
+        name = self.Meta.model.sanitize_name(data["name"])
+        data["name"] = name
+        version = data.get("version")
 
         if self.Meta.model.objects.filter(
             author=user, name=name, version=version