diff --git a/changelog/4248.trivial.rst b/changelog/4248.trivial.rst
new file mode 100644
index 00000000000..ecd9399a7c6
--- /dev/null
+++ b/changelog/4248.trivial.rst
@@ -0,0 +1 @@
+Remove use of unnecessary compat shim, six.binary_type
diff --git a/src/_pytest/pathlib.py b/src/_pytest/pathlib.py
index ba9dcdfb312..7cf3f40b62d 100644
--- a/src/_pytest/pathlib.py
+++ b/src/_pytest/pathlib.py
@@ -159,7 +159,7 @@ def create_cleanup_lock(p):
     else:
         pid = os.getpid()
         spid = str(pid)
-        if not isinstance(spid, six.binary_type):
+        if not isinstance(spid, bytes):
             spid = spid.encode("ascii")
         os.write(fd, spid)
         os.close(fd)