diff --git a/.test-conda-env-py3.yml b/.test-conda-env-py3.yml
index cd7ca6a9aaeec7b46358be6f9a88287d15f29c5e..26220a4bfc92c992cd4d0c4bf5b3ae2aeeace1a8 100644
--- a/.test-conda-env-py3.yml
+++ b/.test-conda-env-py3.yml
@@ -12,6 +12,9 @@ dependencies:
 - pyopencl
 - islpy
 
+# for Pytential
+- cython
+
 # Only needed to make pylint succeed
 - matplotlib