diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f6996c7..292d02b 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -4219,7 +4219,7 @@
 	/* Convert item to Unicode. */
 	if (! PyUnicode_Check(item) && ! PyString_Check(item)) {
 	    PyErr_Format(PyExc_TypeError,
-			 "sequence item %i: expected string or Unicode,"
+			 "sequence item %zd: expected string or Unicode,"
 			 " %.80s found",
 			 i, item->ob_type->tp_name);
 	    goto onError;