diff --git a/Pipfile b/Pipfile
index 6ad3546..f28b466 100644
--- a/Pipfile
+++ b/Pipfile
@@ -4,6 +4,7 @@ url = "https://pypi.org/simple"
 verify_ssl = true
 
 [dev-packages]
+smart_open = "*"
 
 [packages]
 jsonschema = "*"