diff --git a/src/json/builder.rs b/src/json/builder.rs
index 12081372..3bba0ab8 100644
--- a/src/json/builder.rs
+++ b/src/json/builder.rs
@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use std::collections::BTreeMap;
-use std::str::StrAllocating;
 
 use json::value::{ToJson, Value};
 
@@ -56,20 +55,20 @@ impl ObjectBuilder {
         Value::Object(self.object)
     }
 
-    pub fn insert<K: StrAllocating, V: ToJson>(self, key: K, value: V) -> ObjectBuilder {
+    pub fn insert<V: ToJson>(self, key: String, value: V) -> ObjectBuilder {
         let mut builder = self;
-        builder.object.insert(key.into_string(), value.to_json());
+        builder.object.insert(key, value.to_json());
         builder
     }
 
-    pub fn insert_array<S: StrAllocating>(self, key: S, f: |ArrayBuilder| -> ArrayBuilder) -> ObjectBuilder {
+    pub fn insert_array(self, key: String, f: |ArrayBuilder| -> ArrayBuilder) -> ObjectBuilder {
         let builder = ArrayBuilder::new();
-        self.insert(key.into_string(), f(builder).unwrap())
+        self.insert(key, f(builder).unwrap())
     }
 
-    pub fn insert_object<S: StrAllocating>(self, key: S, f: |ObjectBuilder| -> ObjectBuilder) -> ObjectBuilder {
+    pub fn insert_object(self, key: String, f: |ObjectBuilder| -> ObjectBuilder) -> ObjectBuilder {
         let builder = ObjectBuilder::new();
-        self.insert(key.into_string(), f(builder).unwrap())
+        self.insert(key, f(builder).unwrap())
     }
 }
 
diff --git a/src/json/mod.rs b/src/json/mod.rs
index d9d4da2c..feca55f6 100644
--- a/src/json/mod.rs
+++ b/src/json/mod.rs
@@ -157,8 +157,8 @@ pub struct MyStruct  {
 impl ToJson for MyStruct {
     fn to_json( &self ) -> Value {
         ObjectBuilder::new()
-            .insert("attr1", &self.attr1)
-            .insert("attr2", &self.attr2)
+            .insert("attr1".to_string(), &self.attr1)
+            .insert("attr2".to_string(), &self.attr2)
             .unwrap()
     }
 }
@@ -265,9 +265,9 @@ pub struct TestStruct1  {
 impl ToJson for TestStruct1 {
     fn to_json( &self ) -> json::Value {
         json::builder::ObjectBuilder::new()
-            .insert("data_int", &self.data_int)
-            .insert("data_str", &self.data_str)
-            .insert("data_vector", &self.data_vector)
+            .insert("data_int".to_string(), &self.data_int)
+            .insert("data_str".to_string(), &self.data_str)
+            .insert("data_vector".to_string(), &self.data_vector)
             .unwrap()
     }
 }
@@ -281,7 +281,7 @@ fn main() {
         data_vector: vec![2,3,4,5],
     };
     let json: json::Value = test.to_json();
-    let json_str: String = json.to_string().into_string();
+    let json_str: String = json.to_string();
 
     // Deserialize like before.