diff --git a/.readthedocs.yml b/.readthedocs.yml
index dcabba2..e07d9d5 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -21,3 +21,8 @@ python:
 sphinx:
   builder: html
   configuration: doc/source/conf.py
+
+formats:
+  - pdf
+  - epub
+  -
\ No newline at end of file
diff --git a/environment.yml b/environment.yml
index 018eb5f..60f7de2 100644
--- a/environment.yml
+++ b/environment.yml
@@ -1,7 +1,6 @@
 name: filter_functions
 
 channels:
-  - defaults
   - conda-forge
 
 dependencies: