diff --git a/docs/requirements.txt b/docs/requirements.txt
index f51957e..3979f83 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -7,3 +7,4 @@ jupytext
 jupyter
 astropy
 sbpy
+matplotlib
diff --git a/pyproject.toml b/pyproject.toml
index 5447288..f063280 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,7 +18,8 @@ dependencies = [
     "numpy",
     "lsst-rsp",
     "astropy",
-    "sbpy"
+    "sbpy",
+    "matplotlib" # plotting for demo notebooks
 ]
 
 [project.urls]