diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index f08a3692dd2118340f930b55d37df1583c28faa0..cc9700f452950d69e1c378eb89acb18095ff762c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -11,7 +11,7 @@ flatpak:
     FLATPAK_MODULE: 'epiphany'
     # Make sure to keep this in sync with the Flatpak manifest, all arguments
     # are passed except the config-args because we build it ourselves
-    MESON_ARGS: '-Dunit_tests=enabled -Dnetwork_tests=enabled'
+    MESON_ARGS: '-Dunit_tests=enabled -Dnetwork_tests=enabled --werror'
     APP_ID: 'org.gnome.Epiphany'
 
 review: