diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 9a254f21dc..e800d4add7 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -24,5 +24,11 @@ build:
     - "mamba run --name mxcubecore poetry install --only=docs,main"
     - "mamba run --name mxcubecore poetry run sphinx-build -T -E -b html -c ./docs/ ./docs/source/ ${READTHEDOCS_OUTPUT}/html/"
 
+# `conda.environment` is probably not used, since we use custom commands only,
+# but it seems to be required (wrongly) by ReadTheDocs config file validation.
+# https://github.com/readthedocs/readthedocs.org/pull/10979#issuecomment-1896036953
+conda:
+  environment: "conda-environment-dev.yml"
+
 
 ...  # EOF