diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 54db7f1..7ef772a 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -6,7 +6,7 @@ build:
     python: "3.13"
   jobs:
     pre_build:
-      - "sed -i '/local_extensions:/,/^[^ ]/d' book/_config.yml"
+      - "sed -i '\\/local_extensions:/,\\/^[^ ]/d' book/_config.yml"
       - "jupyter-book config sphinx book/"
 
 python:
diff --git a/book/features/pull_request_build.md b/book/features/pull_request_build.md
index 6697d9a..0cf1470 100644
--- a/book/features/pull_request_build.md
+++ b/book/features/pull_request_build.md
@@ -38,7 +38,9 @@ sphinx:
   builder: html
   fail_on_warning: true
   configuration: book/conf.py
-```
+  ```
+
+You might need to add `standard-imghdr` to your `requirements.txt` file if the build fails when you've configured it in Read the Docs (if the error tells you `ModuleNotFoundError: No module named 'imghdr'`)
 
 ### Setup Read The Docs account