diff --git a/doc/conf.py b/doc/conf.py
index 584165362..bd0e5c493 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -18,7 +18,7 @@ import shlex
 
 # These 4 lines added to enable ReadTheDocs to work.
 import mock
-MOCK_MODULES = ["libraylib", "IPython", "numpy", "typing", "funcsigs", "subprocess32", "protobuf", "colorama", "graphviz", "ray.internal.graph_pb2"]
+MOCK_MODULES = ["libraylib", "IPython", "numpy", "typing", "funcsigs", "subprocess32", "protobuf", "colorama", "graphviz", "cloudpickle", "ray.internal.graph_pb2"]
 for mod_name in MOCK_MODULES:
   sys.modules[mod_name] = mock.Mock()