Index: sphinx/environment.py
===================================================================
--- sphinx/environment.py	(revision 64090)
+++ sphinx/environment.py	(working copy)
@@ -1047,7 +1047,7 @@
     def check_consistency(self):
         """Do consistency checks."""
 
-        for docname in self.all_docs:
+        for docname in sorted(self.all_docs):
             if docname not in self.files_to_rebuild:
                 if docname == self.config.master_doc:
                     # the master file is not included anywhere ;)