diff --git a/src/rustdoc/rustdoc.rc b/src/rustdoc/rustdoc.rc
index 8fc39afbd07..5be7a7d3432 100644
--- a/src/rustdoc/rustdoc.rc
+++ b/src/rustdoc/rustdoc.rc
@@ -12,4 +12,5 @@ mod extract;
 mod attr_parser;
 mod doc;
 mod gen;
-mod fold;
\ No newline at end of file
+mod fold;
+mod tystr_pass;
\ No newline at end of file
diff --git a/src/rustdoc/tystr_pass.rs b/src/rustdoc/tystr_pass.rs
new file mode 100644
index 00000000000..8894fe88ca8
--- /dev/null
+++ b/src/rustdoc/tystr_pass.rs
@@ -0,0 +1,69 @@
+import rustc::syntax::ast;
+
+export run;
+
+fn run(doc: doc::cratedoc, crate: @ast::crate) -> doc::cratedoc {
+    let fold = fold::fold({
+        fold_fn: fn~(
+            f: fold::fold<@ast::crate>,
+            d: doc::fndoc
+        ) -> doc::fndoc {
+            fold_fn(f, d)
+        }
+        with *fold::default_seq_fold(crate)
+    });
+    fold.fold_crate(fold, doc)
+}
+
+fn fold_fn(
+    fold: fold::fold<@ast::crate>,
+    doc: doc::fndoc
+) -> doc::fndoc {
+    import rustc::middle::ast_map;
+    import rustc::syntax::print::pprust;
+
+    let crate = fold.ctxt;
+
+    let map = ast_map::map_crate(*crate);
+
+    fn add_ret_ty(
+        doc: option<doc::retdoc>,
+        tystr: str
+    ) -> option<doc::retdoc> {
+        alt doc {
+          some(doc) {
+            fail "unimplemented";
+          }
+          none. {
+            some({
+                desc: none,
+                ty: some(tystr)
+            })
+          }
+        }
+    }
+
+    ~{
+        return: alt map.get(doc.id) {
+          ast_map::node_item(@{
+            node: ast::item_fn(decl, _, _), _
+          }) {
+            add_ret_ty(doc.return, pprust::ty_to_str(decl.output))
+          }
+        }
+        with *doc
+    }
+}
+
+#[cfg(test)]
+mod tests {
+
+    #[test]
+    fn should_add_fn_ret_types() {
+        let source = "fn a() -> int { }";
+        let ast = parse::from_str(source);
+        let doc = extract::extract(ast, "");
+        let doc = run(doc, ast);
+        assert option::get(doc.topmod.fns[0].return).ty == some("int");
+    }
+}