diff --git a/setup.cfg b/setup.cfg
index 92154b4f..f58723a0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -46,6 +46,8 @@ useful =
     aioca >=1.6
 # Dev and docs dependencies
 dev =
+    # Pytest 9.1.0 deprecates some APIs that some of our plugins require
+    pytest<9.1.0
     pytest-cov
     pytest-flake8
     # Flake8 5.0 starts printing error, so pin to avoid it: