diff --git a/docs/changelog.rst b/docs/changelog.rst
index 08e5a490..d5ee2b23 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -14,6 +14,7 @@ dev
 -  Use new update_one, update_many on document/queryset update #1491
 -  Use insert_one, insert_many in Document.insert #1491
 -  Fix reload(fields) affect changed fields #1371
+-  Fix Read-only access to database fails when trying to create indexes #1338
 
 Changes in 0.15.0
 =================
diff --git a/mongoengine/document.py b/mongoengine/document.py
index 109f8f82..0d471c3a 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -195,7 +195,10 @@ class Document(BaseDocument):
 
             # Ensure indexes on the collection unless auto_create_index was
             # set to False.
-            if cls._meta.get('auto_create_index', True):
+            # Also there is no need to ensure indexes on slave.
+            db = cls._get_db()
+            if cls._meta.get('auto_create_index', True) and\
+                    db.client.is_primary:
                 cls.ensure_indexes()
 
         return cls._collection