diff --git a/runtests.py b/runtests.py
index 9030242a8..5c1748f5a 100755
--- a/runtests.py
+++ b/runtests.py
@@ -60,7 +60,8 @@ if not settings.configured:
             'wagtail.wagtailembeds',
             'wagtail.wagtailsearch',
             'wagtail.wagtailredirects',
-        ]
+        ],
+        COMPRESS_ENABLED=False,
     )