diff --git a/upper-constraints.txt b/upper-constraints.txt
index 2f53a9e3e1..9b52043c26 100644
--- a/upper-constraints.txt
+++ b/upper-constraints.txt
@@ -370,7 +370,7 @@ SecretStorage===3.3.3
 opentracing===2.4.0
 XStatic-Rickshaw===1.5.1.0
 iso8601===1.1.0
-tooz===4.1.0
+tooz===4.2.0
 linecache2===1.0.0
 oauth2client===4.1.3
 idna===3.4