diff --git a/haystack/document_store/sql.py b/haystack/document_store/sql.py
index f23ab422d..57f85bdcd 100644
--- a/haystack/document_store/sql.py
+++ b/haystack/document_store/sql.py
@@ -406,7 +406,7 @@ class SQLDocumentStore(BaseDocumentStore):
         """
         Return the number of labels in the document store
         """
-        index = index or self.index
+        index = index or self.label_index
         return self.session.query(LabelORM).filter_by(index=index).count()
 
     def _convert_sql_row_to_document(self, row) -> Document: