diff --git a/src/code-index.md b/src/code-index.md
index b1eb3546a..6a500abba 100644
--- a/src/code-index.md
+++ b/src/code-index.md
@@ -8,5 +8,6 @@ Item            |  Kind    | Short description           | Chapter            |
 ----------------|----------|-----------------------------|--------------------|-------------------
 `CodeMap` | struct | The CodeMap maps the AST nodes to their source code | [The parser](the-parser.html) | [src/libsyntax/codemap.rs](https://github.com/rust-lang/rust/blob/master/src/libsyntax/codemap.rs)
 `ParseSess` | struct | This struct contains information about a parsing session | [The parser](the-parser.html) | [src/libsyntax/parse/mod.rs](https://github.com/rust-lang/rust/blob/master/src/libsyntax/parse/mod.rs)
+`StringReader` | struct | This is the lexer used during parsing. It consumes characters from the raw source code being compiled and produces a series of tokens for use by the rest of the parser | [The parser](the-parser.html) |  [src/libsyntax/parse/lexer/mod.rs](https://github.com/rust-lang/rust/blob/master/src/libsyntax/parse/lexer/mod.rs)
 `TraitDef` | struct | This struct contains a trait's definition with type information | [The `ty` modules](ty.html) |  [src/librustc/ty/trait_def.rs](https://github.com/rust-lang/rust/blob/master/src/librustc/ty/trait_def.rs)
 `TyCtxt<'cx, 'tcx, 'tcx>` | type | The "typing context". This is the central data structure in the compiler. It is the context that you use to perform all manner of queries. | [The `ty` modules](ty.html) | [src/librustc/ty/context.rs](https://github.com/rust-lang/rust/blob/master/src/librustc/ty/context.rs)