diff --git a/tox.ini b/tox.ini
index 353977519..753698cf7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,8 @@ deps =
     mitmproxy >= 4.0.4, < 5; python_version >= '3.6' and python_version < '3.7' and platform_system != 'Windows' and implementation_name != 'pypy'
     # Extras
     botocore>=1.4.87
+    # Peek support breaks tests.
+    queuelib < 1.6.0
 passenv =
     S3_TEST_FILE_URI
     AWS_ACCESS_KEY_ID