diff --git a/TODO.md b/TODO.md
index 6c4bbe29..8ddc56d6 100644
--- a/TODO.md
+++ b/TODO.md
@@ -19,6 +19,10 @@
     method using vagrant
 
 
+## Documentation
+
+- tk Write up how to write an extension. Document extra arguments feature.
+
 ## Drivers
 
 - mw The `fousb` driver needs to be ported to Python 12.  post weewx 5.0 release
diff --git a/dev_requirements.txt b/dev_requirements.txt
index 980997e1..70bb04cb 100644
--- a/dev_requirements.txt
+++ b/dev_requirements.txt
@@ -1,10 +1,10 @@
-configobj >=5.0
-# This is the renamed "Cheetah" package:
-ct3 >= 3.1
-ephem >= 4.1
+configobj>=5.0
+CT3>=3.1
+ephem>=4.1
 mkdocs
 mkdocs-material
-pillow >= 5.2
-pymysql >= 1.0
-pyserial >= 3.4
-pyusb >= 1.0.2
\ No newline at end of file
+mkdocs-material-extensions
+Pillow>=5.2
+PyMySQL[cryptography]
+pyserial>=3.4
+pyusb>=1.0.2