diff --git a/specs/simple-serialize.md b/specs/simple-serialize.md
index f479c5d00..119022248 100644
--- a/specs/simple-serialize.md
+++ b/specs/simple-serialize.md
@@ -189,7 +189,7 @@ We first define helper functions:
    * `List[B, N]` and `Vector[B, N]`, where `B` is a basic type: `(N * size_of(B) + 31) // 32` (dividing by chunk size, rounding up)
    * `List[C, N]` and `Vector[C, N]`, where `C` is a composite type: `N`
    * containers: `len(fields)`
-* `bitfield_bytes(bits)`: return the bits of the bitlist or bitvector, packed in bytes, aligned to the start. Exclusive length-delimiting bit for bitlists.
+* `bitfield_bytes(bits)`: return the bits of the bitlist or bitvector, packed in bytes, aligned to the start. Length-delimiting bit for bitlists is excluded.
 * `pack`: Given ordered objects of the same basic type, serialize them, pack them into `BYTES_PER_CHUNK`-byte chunks, right-pad the last chunk with zero bytes, and return the chunks.
 * `next_pow_of_two(i)`: get the next power of 2 of `i`, if not already a power of 2, with 0 mapping to 1. Examples: `0->1, 1->1, 2->2, 3->4, 4->4, 6->8, 9->16`
 * `merkleize(chunks, limit=None)`: Given ordered `BYTES_PER_CHUNK`-byte chunks, merkleize the chunks, and return the root: