diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index 2a1dbcb..532e637 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -1078,7 +1078,7 @@
     else if (PyObject_AsCharBuffer(sub_obj, &sub, &sub_len))
         return NULL;
 
-    _adjust_indices(&start, &end, PyString_GET_SIZE(self));
+    _adjust_indices(&start, &end, PyBytes_GET_SIZE(self));
 
     return PyInt_FromSsize_t(
         stringlib_count(str + start, end - start, sub, sub_len)