diff --git a/src/_pytest/capture.py b/src/_pytest/capture.py
index 5b359fa185..7ff0d100ad 100644
--- a/src/_pytest/capture.py
+++ b/src/_pytest/capture.py
@@ -177,7 +177,7 @@ def name(self) -> str:
     def mode(self) -> str:
         # TextIOWrapper doesn't expose a mode, but at least some of our
         # tests check it.
-        assert hasattr(self.buffer, 'mode')
+        assert hasattr(self.buffer, "mode")
         return cast(str, self.buffer.mode.replace("b", ""))