diff --git a/pandora_client/__init__.py b/pandora_client/__init__.py
index 60225ac..458247a 100755
--- a/pandora_client/__init__.py
+++ b/pandora_client/__init__.py
@@ -770,7 +770,7 @@ class Client(object):
                 ],
                 'operator': '|'
             },
-            'keys': ['item', 'id'],
+            'keys': ['item', 'id', 'extension'],
             'range': [0, 5000]
         })['data']['items']
         d = self.api.findDocuments({
@@ -781,11 +781,14 @@ class Client(object):
                 ],
                 'operator': '|'
             },
-            'keys': ['id', 'oshash'],
+            'keys': ['id', 'oshash', 'extension'],
             'range': [0, len(files)]
         })['data']['items']
-        available = set(f['oshash'] for f in d)
-        missing = [(f['id'], f['item']) for f in files if f['id'] not in available]
+        available = set(f['oshash']
+                        for f in d if f['extension'] in DOCUMENT_FORMATS)
+        missing = [(f['id'], f['item']) for f in files \
+                   if f['id'] not in available \
+                      and f['extension'] in DOCUMENT_FORMATS]
         return missing
 
     def _add_document(self, f, item=None):