diff --git a/environment.yml b/environment.yml
index 3bad2149..3b37c36c 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,6 +5,7 @@ dependencies:
   - jupyter-book
   - jupyterlab
   - jupyter_server<2
+  - numpy
   - pip
   - pip:
       - sphinx-pythia-theme