diff --git a/docs/development/languages/fidl/reference/wire-format/README.md b/docs/development/languages/fidl/reference/wire-format/README.md
index 6d8afed27b5e3ebf9f303f6d0f280463e05cd81d..c0d239320bbe4513ef34684ee14176f73a4d2ac5 100644
--- a/docs/development/languages/fidl/reference/wire-format/README.md
+++ b/docs/development/languages/fidl/reference/wire-format/README.md
@@ -498,9 +498,9 @@ to the selected option.
 
 An envelope is a container for out-of-line data, used internally by tables
 and extensible unions.
-It is not exposed to the FIDL lanuage.
+It is not exposed to the FIDL language.
 
-It has a fixed, 24 byte format, and is not nullable:
+It has a fixed, 16 byte format, and is not nullable:
 
 ![drawing](envelope.png)
 
diff --git a/docs/development/languages/fidl/reference/wire-format/envelope.png b/docs/development/languages/fidl/reference/wire-format/envelope.png
index 319c2389576b4dbcd662e49efb49fa5073540328..43cab4e290eac97357171c414e813588b26520db 100644
Binary files a/docs/development/languages/fidl/reference/wire-format/envelope.png and b/docs/development/languages/fidl/reference/wire-format/envelope.png differ