diff --git a/loxi_ir/ir_offset.py b/loxi_ir/ir_offset.py
index 0f27f5e..e705fcc 100644
--- a/loxi_ir/ir_offset.py
+++ b/loxi_ir/ir_offset.py
@@ -100,6 +100,7 @@
     of_match_v3_t = (8, False),
     of_octets_t = (0, False),
     of_bitmap_128_t = (16, True),
+    of_checksum_128_t = (16, True),
 )
 
 def type_dec_to_count_base(m_type):