diff --git a/docs/src/reference.md b/docs/src/reference.md
index 610e23f..7a490af 100644
--- a/docs/src/reference.md
+++ b/docs/src/reference.md
@@ -42,6 +42,7 @@ Base.position(::NoopStream)
 ```@docs
 TranscodingStreams.Codec
 TranscodingStreams.expectedsize
+TranscodingStreams.pledgeinsize
 TranscodingStreams.minoutsize
 TranscodingStreams.initialize
 TranscodingStreams.finalize