diff --git a/justfile b/justfile
index aec1d14..cc501a1 100644
--- a/justfile
+++ b/justfile
@@ -21,7 +21,7 @@ typecheck:
 
 # Run unit tests
 test *args:
-    uv run pytest -W error {{ args }}
+    uv run pytest {{ args }}
 
 # Run lint, typecheck and test
 check: lint typecheck test
diff --git a/pyproject.toml b/pyproject.toml
index ad206fe..99755f0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -82,6 +82,8 @@ module-name = "connectrpc"
 strict = true
 testpaths = ["test"]
 timeout = "1800"     # 30 min
+# Turn all warnings into errors
+filterwarnings = ["error"]
 
 [tool.ruff.format]
 skip-magic-trailing-comma = true