diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index e2a74ba4dfc9..ce1302c8db87 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -190,6 +190,8 @@ pub struct TyParam {
     pub span: Span
 }
 
+/// Represents lifetimes and type parameters attached to a declaration
+/// of a function, enum, trait, etc.
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash)]
 pub struct Generics {
     pub lifetimes: Vec<Lifetime>,
@@ -288,7 +290,7 @@ pub enum Pat_ {
     PatWild,
     PatWildMulti,
     // A PatIdent may either be a new bound variable,
-    // or a nullary enum (in which case the second field
+    // or a nullary enum (in which case the third field
     // is None).
     // In the nullary enum case, the parser can't determine
     // which it is. The resolver determines this, and
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 31226a620ea8..55bc5e3c3036 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -841,9 +841,9 @@ fn expand_pat(p: Gc<ast::Pat>, fld: &mut MacroExpander) -> Gc<ast::Pat> {
     }
 }
 
-// a tree-folder that applies every rename in its (mutable) list
-// to every identifier, including both bindings and varrefs
-// (and lots of things that will turn out to be neither)
+/// A tree-folder that applies every rename in its (mutable) list
+/// to every identifier, including both bindings and varrefs
+/// (and lots of things that will turn out to be neither)
 pub struct IdentRenamer<'a> {
     renames: &'a mtwt::RenameList,
 }
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index f9d7078da3dc..04e6612daf1f 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -794,7 +794,7 @@ pub fn noop_fold_pat<T: Folder>(p: Gc<Pat>, folder: &mut T) -> Gc<Pat> {
         PatIdent(binding_mode, ref pth1, ref sub) => {
             PatIdent(binding_mode,
                      Spanned{span: folder.new_span(pth1.span),
-                                       node: folder.fold_ident(pth1.node)},
+                             node: folder.fold_ident(pth1.node)},
                      sub.map(|x| folder.fold_pat(x)))
         }
         PatLit(e) => PatLit(folder.fold_expr(e)),