diff --git a/ci/requirements/readthedocs.yml b/ci/requirements/readthedocs.yml
index 611c69307d..5a7e3975f7 100644
--- a/ci/requirements/readthedocs.yml
+++ b/ci/requirements/readthedocs.yml
@@ -17,9 +17,9 @@ dependencies:
   - cartopy>=0.12
   - proj4<6
   - cf-units>=2
-  - cftime==1.1.3
+  - cftime
   - dask>=2
-  - matplotlib
+  - matplotlib<3.3
   - netcdf4
   - numpy>=1.14
   - scipy