diff --git a/docs/rtd_environment.yml b/docs/rtd_environment.yml
index b59199a2c..114c292d0 100644
--- a/docs/rtd_environment.yml
+++ b/docs/rtd_environment.yml
@@ -1,7 +1,8 @@
 name: xtensor-docs
 
 channels:
-- conda-forge
+  - conda-forge
 
 dependencies:
-- breathe
+  - breathe
+  - sphinx_rtd_theme
diff --git a/readthedocs.yml b/readthedocs.yml
index 03c0ad19a..6cc465c9b 100644
--- a/readthedocs.yml
+++ b/readthedocs.yml
@@ -1,2 +1,9 @@
+version: 2
+
+build:
+  os: "ubuntu-22.04"
+  tools:
+    python: "mambaforge-22.9"
+
 conda:
-  file: docs/rtd_environment.yml
+  environment: docs/rtd_environment.yml