diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 477827a0..26f2c8b 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -1556,7 +1556,7 @@
 }
 
 static int
-unicode_widen(PyObject **p_unicode, int maxchar)
+unicode_widen(PyObject **p_unicode, unsigned int maxchar)
 {
     PyObject *result;
     assert(PyUnicode_IS_READY(*p_unicode));