diff --git a/requirements-app.txt b/requirements-app.txt
index fec9a1d68..4a7a7e5c7 100644
--- a/requirements-app.txt
+++ b/requirements-app.txt
@@ -32,5 +32,5 @@ awscli-cwlogs==1.4.6
 git+https://github.com/alphagov/notifications-utils.git@43.5.9#egg=notifications-utils==43.5.9
 
 # gds-metrics requires prometheseus 0.2.0, override that requirement as 0.7.1 brings significant performance gains
-prometheus-client==0.8.0
+prometheus-client==0.9.0
 gds-metrics==0.2.4