diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index d023ff0..8c5a6bb 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -5,6 +5,8 @@ build:
   tools:
     python: "3.10"
   jobs:
+    pre_system_dependencies:
+      - sudo apt install -y libx11-6
     post_install:
       - python docs/get_wheel_artifact.py haosulab/MPlib --py cp310 --wait-sec 600
       - pip install wheelhouse/mplib*.whl
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 343e9a8..2e2cb99 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -2,3 +2,4 @@ myst-parser
 furo
 sphinx-copybutton
 sphinxext-opengraph
+sapien~=3.0.0.dev