diff --git a/ckan/logic/action/get.py b/ckan/logic/action/get.py
index aeeabc9e8e2..99e5491f653 100644
--- a/ckan/logic/action/get.py
+++ b/ckan/logic/action/get.py
@@ -999,18 +999,12 @@ def vocabulary_list(context, data_dict):
 
 def vocabulary_show(context, data_dict):
     model = context['model']
-
-    if data_dict.has_key('id'):
-        vocabulary = model.vocabulary.Vocabulary.get(data_dict['id'])
-        if vocabulary is None:
-            raise NotFound
-    elif data_dict.has_key('name'):
-        vocabulary = model.vocabulary.Vocabulary.get(data_dict['name'])
-        if vocabulary is None:
-            raise NotFound
-    else:
-        raise NotFound
-
+    vocab_id = data_dict.get('id')
+    if not vocab_id:
+        raise ValidationError({'id': _('id not in data')})
+    vocabulary = model.vocabulary.Vocabulary.get(vocab_id)
+    if vocabulary is None:
+        raise NotFound(_('Could not find vocabulary "%s"') % vocab_id)
     vocabulary_dict = vocabulary_dictize(vocabulary, context)
     return vocabulary_dict
 
diff --git a/ckan/tests/functional/api/model/test_vocabulary.py b/ckan/tests/functional/api/model/test_vocabulary.py
index b351eabea06..608f98698fa 100644
--- a/ckan/tests/functional/api/model/test_vocabulary.py
+++ b/ckan/tests/functional/api/model/test_vocabulary.py
@@ -60,7 +60,7 @@ def _create_vocabulary(self, vocab_name=None, user=None):
         params = {'id': created_vocab['id']}
         response = self._post('/api/action/vocabulary_show', params)
         # Check that retrieving the vocab by name gives the same result.
-        by_name_params = {'name': created_vocab['name']}
+        by_name_params = {'id': created_vocab['name']}
         assert response == self._post('/api/action/vocabulary_show',
                 by_name_params)
         # Check that it matches what we created.
@@ -101,7 +101,7 @@ def _update_vocabulary(self, params, user=None):
         params = {'id': updated_vocab['id']}
         response = self._post('/api/action/vocabulary_show', params)
         # Check that retrieving the vocab by name gives the same result.
-        by_name_params = {'name': updated_vocab['name']}
+        by_name_params = {'id': updated_vocab['name']}
         assert response == self._post('/api/action/vocabulary_show',
                 by_name_params)
         # Check that it matches what we created.
diff --git a/ckan/tests/functional/test_tag_vocab.py b/ckan/tests/functional/test_tag_vocab.py
index 976a8122edf..226f018544f 100644
--- a/ckan/tests/functional/test_tag_vocab.py
+++ b/ckan/tests/functional/test_tag_vocab.py
@@ -187,7 +187,7 @@ def teardown_class(cls):
         model.repo.rebuild_db()
 
     def _get_vocab_id(self, vocab_name):
-        params = json.dumps({'name': vocab_name})
+        params = json.dumps({'id': vocab_name})
         response = self.app.post('/api/action/vocabulary_show', params=params)
         assert json.loads(response.body)['success']
         return json.loads(response.body)['result']['id']