diff --git a/src/_pytest/_py/path.py b/src/_pytest/_py/path.py
index 0792da22810..a3c72dcbcf7 100644
--- a/src/_pytest/_py/path.py
+++ b/src/_pytest/_py/path.py
@@ -1221,7 +1221,7 @@ def pyimport(self, modname=None, ensuresyspath=True):
                 mod.__file__ = str(self)
                 sys.modules[modname] = mod
                 try:
-                    with open(str(self), 'rb') as f:
+                    with open(str(self), "rb") as f:
                         exec(f.read(), mod.__dict__)
                 except:
                     del sys.modules[modname]