diff --git a/datagateway_api/common/icat/query.py b/datagateway_api/common/icat/query.py
index fe46c1fe..1a8090ee 100644
--- a/datagateway_api/common/icat/query.py
+++ b/datagateway_api/common/icat/query.py
@@ -329,4 +329,4 @@ def flatten_query_included_fields(self, includes):
             ICAT query
         """
 
-        return [m for n in (field.split(".") for field in includes) for m in n]
+        return [m for n in (field.split(".") for field in sorted(includes)) for m in n]