diff --git a/requirements.txt b/requirements.txt
index 5de34dc..ff6857d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
 requests==2.21.0
-marshmallow==2.18.1
+marshmallow==3.4.0
 six==1.12.0
 pytz==2018.9