diff --git a/Tools/PROCTools/python/RunTier0Tests.py b/Tools/PROCTools/python/RunTier0Tests.py
index c79f3f964c43bf04cd5c97ea15455d518aa241fb..6ef49a3f5c97f93e44404c97ff2843eb90e98188 100755
--- a/Tools/PROCTools/python/RunTier0Tests.py
+++ b/Tools/PROCTools/python/RunTier0Tests.py
@@ -330,7 +330,7 @@ def RunFrozenTier0PolicyTest(q,inputFormat,maxEvents,CleanRunHeadDir,UniqID,Diff
         exclusion_list = []
         with open(diff_rules_file) as f:
             for line in f:
-                exclusion_list.append('"'+line.rstrip()+'"')
+                exclusion_list.append(r"'{}'".format(line.rstrip()))
     else:
         logging.info("No diff rules file exists, using the default list")
         exclusion_list = [r"'index_ref'", r"'(.*)_timings\.(.*)'", r"'(.*)_mems\.(.*)'"]