diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -4354,7 +4354,7 @@ posix_getlogin(PyObject *self, PyObject 
                         "unable to determine login name");
     }
     else
-        result = PyUnicode_FromString(name);
+        result = PyUnicode_DecodeFSDefault(name);
     errno = old_errno;
 
     return result;