diff --git a/Lib/test/test_cmd_line_script.py b/Lib/test/test_cmd_line_script.py
index 17dfbc2..6e097e3 100644
--- a/Lib/test/test_cmd_line_script.py
+++ b/Lib/test/test_cmd_line_script.py
@@ -363,6 +363,15 @@
             self.assertTrue(text[1].startswith('  File '))
             self.assertTrue(text[3].startswith('NameError'))
 
+    def test_non_utf8(self):
+        # Issue #16218
+        with temp_dir() as script_dir:
+            script_name = _make_test_script(script_dir,
+                    '\udcf1\udcea\udcf0\udce8\udcef\udcf2')
+            self._check_script(script_name, script_name, script_name,
+                               script_dir, None,
+                               importlib.machinery.SourceFileLoader)
+
 def test_main():
     support.run_unittest(CmdLineTest)
     support.reap_children()
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index b1ca125..7c4fb4a 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1358,16 +1358,21 @@
 {
     PyInterpreterState *interp;
     PyThreadState *tstate;
-    PyObject *loader_type, *loader;
+    PyObject *filename_obj, *loader_type, *loader;
     int result = 0;
+
+    filename_obj = PyUnicode_DecodeFSDefault(filename);
+    if (filename_obj == NULL)
+        return -1;
     /* Get current thread state and interpreter pointer */
     tstate = PyThreadState_GET();
     interp = tstate->interp;
     loader_type = PyObject_GetAttrString(interp->importlib, loader_name);
     if (loader_type == NULL) {
+        Py_DECREF(filename_obj);
         return -1;
     }
-    loader = PyObject_CallFunction(loader_type, "ss", "__main__", filename);
+    loader = PyObject_CallFunction(loader_type, "sN", "__main__", filename_obj);
     Py_DECREF(loader_type);
     if (loader == NULL) {
         return -1;