diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -1372,7 +1372,7 @@
         _RET(value);
     }
     PyErr_Format(PyExc_TypeError,
-                 "string or integer address expected instead of %s instance",
+                 "bytes or integer address expected instead of %s instance",
                  value->ob_type->tp_name);
     return NULL;
 }