diff --git a/development-notes.md b/development-notes.md
index d74ecfc..d85b297 100644
--- a/development-notes.md
+++ b/development-notes.md
@@ -7,7 +7,7 @@ I'm happy to receive patches to Pysolar. Please make sure that your patch does n
 (These notes are just to remind Brandon how releases worked the last time he released a new version of Pysolar.)
 
 1. Patch, test, patch, test, until it works right. Test includes running test/testsolar.py and the validation suite.
-2. To run the validation suite, install Jupyter Notebook and Matplotlib. Then run each cell of `test/validation.ipynb`.
+2. To run the validation suite, install Jupyter Notebook, Matplotlib, and Pandas. Then run each cell of `test/validation.ipynb`.
 3. Commit and push to Github.
 4. Update the version number in setup.py.
 5. Update contributors.markdown if needed.