diff --git a/Modules/readline.c b/Modules/readline.c
index 0d483d7c2e1..3b94d4a0d1d 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -1080,7 +1080,7 @@ done:
     Py_XDECREF(readlinestate_global->endidx);
     readlinestate_global->begidx = PyLong_FromLong((long) start);
     readlinestate_global->endidx = PyLong_FromLong((long) end);
-    result = completion_matches(text, *on_completion);
+    result = completion_matches((char *)text, *on_completion);
 #ifdef WITH_THREAD
     PyGILState_Release(gilstate);
 #endif