diff --git a/conda/lock/environment.yml b/conda/lock/environment.yml
index d261404..2bb86b6 100644
--- a/conda/lock/environment.yml
+++ b/conda/lock/environment.yml
@@ -85,6 +85,7 @@ dependencies:
   - pytest
   - python-snappy
   - pyvo
+  - pzflow=3.4.0
   - qp-prob
   - redmapper
   - sacc