diff --git a/check.sh b/check.sh
index 911396e963..58b00aa1ce 100755
--- a/check.sh
+++ b/check.sh
@@ -39,7 +39,7 @@ if ! ruff check .; then
     echo "* ruff found issues." >> "$GITHUB_STEP_SUMMARY"
     EXIT_STATUS=1
     if $ON_GITHUB_CI; then
-        ruff check --format github --diff .
+        ruff check --output-format github --diff .
     else
         ruff check --diff .
     fi
diff --git a/trio/_threads.py b/trio/_threads.py
index b551d45d38..d44e4b68f8 100644
--- a/trio/_threads.py
+++ b/trio/_threads.py
@@ -409,10 +409,10 @@ def from_thread_check_cancelled() -> None:
     """
     try:
         raise_cancel = PARENT_TASK_DATA.cancel_register[0]
-    except AttributeError:
+    except AttributeError as exc:
         raise RuntimeError(
             "this thread wasn't created by Trio, can't check for cancellation"
-        ) from None
+        ) from exc
     if raise_cancel is not None:
         raise_cancel()