diff --git a/.circleci/config.yml b/.circleci/config.yml
index bb13cae4fec..38380458835 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -81,7 +81,7 @@ jobs:
       - run:
           # Important: all words have to be in lowercase, and separated by "\n".
           name: exclude known exceptions
-          command: 'echo -e "unknwon" > words_to_ignore.txt'
+          command: 'echo -e "unknwon\nreferer\nerrorstring" > words_to_ignore.txt'
       - run:
           name: check documentation spelling errors
           command: 'codespell -I ./words_to_ignore.txt docs/'