diff --git a/smpplib/consts.py b/smpplib/consts.py
index 2987354..8218d93 100644
--- a/smpplib/consts.py
+++ b/smpplib/consts.py
@@ -6,7 +6,7 @@
 # SMPP 3.4, 2.2.1.2
 SEVENBIT_LENGTH = 160
 EIGHTBIT_LENGTH = 140
-UCS2_LENGTH = 70
+UCS2_LENGTH = 140
 
 MULTIPART_HEADER_SIZE = 6