diff --git a/requirements.txt b/requirements.txt
index 8671a953..d22c0b3f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,3 +28,4 @@ six==1.16.0
 sparse==0.13.0
 tomli==2.0.1
 tqdm==4.64.1
+lassen @ git+https://github.com/StanfordAHA/lassen.git@master