diff --git a/rsa/transform.py b/rsa/transform.py
index fe4def8..40f7ca6 100644
--- a/rsa/transform.py
+++ b/rsa/transform.py
@@ -138,7 +138,7 @@
         >>> int2bytes(123456789, 3)
         Traceback (most recent call last):
         ...
-        OverflowError: Need 4 bytes for number, but block size is 3
+        OverflowError: Need 4 bytes for number, but chunk size is 3
 
     :param number:
         Integer value