diff --git a/requirements-dev.txt b/requirements-dev.txt
index e530cb8..2c0c1b2 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -5,4 +5,4 @@ pycodestyle==2.14.0
 pyflakes==3.4.0
 requests-mock==1.12.1
 six==1.17.0
-testtools==2.8.7
+testtools==2.9.0