diff --git a/requirements.txt b/requirements.txt
index 1e36a6b..6ca2b4b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-hsmodels >= 1.0.0
+hsmodels @ git+https://github.com/hydroshare/hsmodels.git@47-annotate-optional-fields-as-optional
 pytest == 6.0.2
 requests == 2.24.0
 email-validator