diff --git a/requirements.txt b/requirements.txt
index bec2f864..f0c3b1ae 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,5 @@
 python-dotenv
-prefect==2.19.1
-prefect[dask]
+prefect[dask]==2.19.1
 dask-jobqueue
 natsort
 pytools@https://github.com/niaid/tomojs-pytools/releases/download/v3.3.0/pytools-3.3.0-py3-none-any.whl