diff --git a/requirements_dev.txt b/requirements_dev.txt
index ddd5d34..c638049 100644
--- a/requirements_dev.txt
+++ b/requirements_dev.txt
@@ -8,3 +8,4 @@ django==2.2.13; python_version>="3.0"
 requests==2.22.0
 responses==0.10.12
 webob
+strict-rfc3339==0.7