diff --git a/src/util/lower_byte_operators.cpp b/src/util/lower_byte_operators.cpp
index a9dc5e4213f7..1d0409c16c66 100644
--- a/src/util/lower_byte_operators.cpp
+++ b/src/util/lower_byte_operators.cpp
@@ -975,7 +975,7 @@ static exprt unpack_rec(
         member,
         little_endian,
         offset_bytes,
-        widest_member->second,
+        (widest_member->second + bits_per_byte - 1) / bits_per_byte,
         bits_per_byte,
         ns,
         true);