diff --git a/docs/source/whatsnew.rst b/docs/source/whatsnew.rst
index a6d4fe8..cb0a959 100644
--- a/docs/source/whatsnew.rst
+++ b/docs/source/whatsnew.rst
@@ -10,6 +10,11 @@ and this project adheres to `Semantic Versioning <https://semver.org/spec/v2.0.0
 1.0.2 - upcoming
 ----------------
 
+Changed
+^^^^^^^
+* matplotlib is now an optional ``doc`` dependency instead of a required
+  dependency. (:pull:`146`)
+
 Added
 ^^^^^
 * Add testing for Python 3.14. (:pull:`144`)
diff --git a/pyproject.toml b/pyproject.toml
index 4e237a5..1d1bcb4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,7 +40,6 @@ classifiers = [
 ]
 dependencies = [
     "numpy",
-    "matplotlib",
     "pandas",
     "pvlib",
 ]
@@ -56,6 +55,7 @@ doc = [
     "sphinx-book-theme==1.1.4",
     "pvlib==0.13.0",
     "pandas==2.3.0",
+    "matplotlib==3.10.7",
 ]
 all = ["solposx[optional,test,doc]"]