diff --git a/environment.yml b/environment.yml
index 526cd10..24de4cf 100644
--- a/environment.yml
+++ b/environment.yml
@@ -3,4 +3,5 @@ name: scadnano-test
 channels:
   - defaults
 dependencies:
+  - python=3.7
   - xlwt=1.3.0=py37_0
\ No newline at end of file
diff --git a/readthedocs.yml b/readthedocs.yml
index f04cf7e..93377a5 100644
--- a/readthedocs.yml
+++ b/readthedocs.yml
@@ -26,4 +26,4 @@ conda:
 build:
   os: "ubuntu-22.04"
   tools:
-    python: "3.7"
\ No newline at end of file
+    python: "mambaforge-22.9"
\ No newline at end of file