diff --git a/src/libextra/json.rs b/src/libextra/json.rs
index f76dc05b2773d..e0e860d102e05 100644
--- a/src/libextra/json.rs
+++ b/src/libextra/json.rs
@@ -135,18 +135,21 @@ impl serialize::Encoder for Encoder {
                          _id: uint,
                          cnt: uint,
                          f: &fn(&mut Encoder)) {
-        // enums are encoded as strings or vectors:
+        // enums are encoded as strings or objects
         // Bunny => "Bunny"
-        // Kangaroo(34,"William") => ["Kangaroo",[34,"William"]]
-
+        // Kangaroo(34,"William") => {"variant": "Kangaroo", "fields": [34,"William"]}
         if cnt == 0 {
             self.wr.write_str(escape_str(name));
         } else {
-            self.wr.write_char('[');
+            self.wr.write_char('{');
+            self.wr.write_str("\"variant\"");
+            self.wr.write_char(':');
             self.wr.write_str(escape_str(name));
             self.wr.write_char(',');
+            self.wr.write_str("\"fields\"");
+            self.wr.write_str(":[");
             f(self);
-            self.wr.write_char(']');
+            self.wr.write_str("]}");
         }
     }
 
@@ -947,14 +950,20 @@ impl serialize::Decoder for Decoder {
         debug!("read_enum_variant(names=%?)", names);
         let name = match self.stack.pop() {
             String(s) => s,
-            List(list) => {
-                for v in list.move_rev_iter() {
-                    self.stack.push(v);
-                }
-                match self.stack.pop() {
-                    String(s) => s,
-                    value => fail!("invalid variant name: %?", value),
+            Object(o) => {
+                let n = match o.find(&~"variant").expect("invalidly encoded json") {
+                    &String(ref s) => s.clone(),
+                    _ => fail!("invalidly encoded json"),
+                };
+                match o.find(&~"fields").expect("invalidly encoded json") {
+                    &List(ref l) => {
+                        for field in l.rev_iter() {
+                            self.stack.push(field.clone());
+                        }
+                    },
+                    _ => fail!("invalidly encoded json")
                 }
+                n
             }
             ref json => fail!("invalid variant: %?", *json),
         };
@@ -1517,7 +1526,7 @@ mod tests {
                 let mut encoder = Encoder(wr);
                 animal.encode(&mut encoder);
             },
-            ~"[\"Frog\",\"Henry\",349]"
+            ~"{\"variant\":\"Frog\",\"fields\":[\"Henry\",349]}"
         );
         assert_eq!(
             do io::with_str_writer |wr| {
@@ -1921,14 +1930,14 @@ mod tests {
         assert_eq!(value, Dog);
 
         let mut decoder =
-            Decoder(from_str("[\"Frog\",\"Henry\",349]").unwrap());
+            Decoder(from_str("{\"variant\":\"Frog\",\"fields\":[\"Henry\",349]}").unwrap());
         let value: Animal = Decodable::decode(&mut decoder);
         assert_eq!(value, Frog(~"Henry", 349));
     }
 
     #[test]
     fn test_decode_map() {
-        let s = ~"{\"a\": \"Dog\", \"b\": [\"Frog\", \"Henry\", 349]}";
+        let s = ~"{\"a\": \"Dog\", \"b\": {\"variant\":\"Frog\",\"fields\":[\"Henry\", 349]}}";
         let mut decoder = Decoder(from_str(s).unwrap());
         let mut map: TreeMap<~str, Animal> = Decodable::decode(&mut decoder);
 
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index f7c76fee18093..9645dab4e8b7b 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -398,30 +398,130 @@ mod test {
     #[test] fn string_to_tts_1 () {
         let (tts,_ps) = string_to_tts_and_sess(@"fn a (b : int) { b; }");
         assert_eq!(to_json_str(@tts),
-                   ~"[\
-                [\"tt_tok\",null,[\"IDENT\",\"fn\",false]],\
-                [\"tt_tok\",null,[\"IDENT\",\"a\",false]],\
-                [\
-                    \"tt_delim\",\
-                    [\
-                        [\"tt_tok\",null,\"LPAREN\"],\
-                        [\"tt_tok\",null,[\"IDENT\",\"b\",false]],\
-                        [\"tt_tok\",null,\"COLON\"],\
-                        [\"tt_tok\",null,[\"IDENT\",\"int\",false]],\
-                        [\"tt_tok\",null,\"RPAREN\"]\
+        ~"[\
+    {\
+        \"variant\":\"tt_tok\",\
+        \"fields\":[\
+            null,\
+            {\
+                \"variant\":\"IDENT\",\
+                \"fields\":[\
+                    \"fn\",\
+                    false\
+                ]\
+            }\
+        ]\
+    },\
+    {\
+        \"variant\":\"tt_tok\",\
+        \"fields\":[\
+            null,\
+            {\
+                \"variant\":\"IDENT\",\
+                \"fields\":[\
+                    \"a\",\
+                    false\
+                ]\
+            }\
+        ]\
+    },\
+    {\
+        \"variant\":\"tt_delim\",\
+        \"fields\":[\
+            [\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"LPAREN\"\
                     ]\
-                ],\
-                [\
-                    \"tt_delim\",\
-                    [\
-                        [\"tt_tok\",null,\"LBRACE\"],\
-                        [\"tt_tok\",null,[\"IDENT\",\"b\",false]],\
-                        [\"tt_tok\",null,\"SEMI\"],\
-                        [\"tt_tok\",null,\"RBRACE\"]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        {\
+                            \"variant\":\"IDENT\",\
+                            \"fields\":[\
+                                \"b\",\
+                                false\
+                            ]\
+                        }\
                     ]\
-                ]\
-            ]"
-                  );
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"COLON\"\
+                    ]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        {\
+                            \"variant\":\"IDENT\",\
+                            \"fields\":[\
+                                \"int\",\
+                                false\
+                            ]\
+                        }\
+                    ]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"RPAREN\"\
+                    ]\
+                }\
+            ]\
+        ]\
+    },\
+    {\
+        \"variant\":\"tt_delim\",\
+        \"fields\":[\
+            [\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"LBRACE\"\
+                    ]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        {\
+                            \"variant\":\"IDENT\",\
+                            \"fields\":[\
+                                \"b\",\
+                                false\
+                            ]\
+                        }\
+                    ]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"SEMI\"\
+                    ]\
+                },\
+                {\
+                    \"variant\":\"tt_tok\",\
+                    \"fields\":[\
+                        null,\
+                        \"RBRACE\"\
+                    ]\
+                }\
+            ]\
+        ]\
+    }\
+]"
+        );
     }
 
     #[test] fn ret_expr() {