diff --git a/pyproject.toml b/pyproject.toml
index aeaeef46..a806c260 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -188,6 +188,7 @@ filterwarnings= [
   # https://github.com/python-trio/trio/issues/3053
   "ignore:The `hash` argument is deprecated in favor of `unsafe_hash` and will be removed in or after August 2025.",
 ]
+asyncio_default_fixture_loop_scope = "function"
 
 [tool.coverage.report]
 exclude_lines = [