diff --git a/docs/.rtd_environment.yaml b/docs/.rtd_environment.yaml
index 77fd4dc6..1881298c 100644
--- a/docs/.rtd_environment.yaml
+++ b/docs/.rtd_environment.yaml
@@ -12,5 +12,6 @@ dependencies:
   - simplejson
   - ctypesgen
   - setuptools
+  - breathe
   - pip:
     - pint