diff --git a/src/main/scala/spray/json/JsValue.scala b/src/main/scala/spray/json/JsValue.scala
index 7cd8cd83..c697e160 100644
--- a/src/main/scala/spray/json/JsValue.scala
+++ b/src/main/scala/spray/json/JsValue.scala
@@ -19,6 +19,7 @@
 package spray.json
 
 import collection.immutable
+import scala.collection.immutable.TreeMap
 
 /**
   * The general type of a JSON AST node.
@@ -53,10 +54,10 @@ case class JsObject(fields: Map[String, JsValue]) extends JsValue {
   def getFields(fieldNames: String*): immutable.Seq[JsValue] = fieldNames.toIterator.flatMap(fields.get).toList
 }
 object JsObject {
-  val empty = JsObject(Map.empty[String, JsValue])
-  def apply(members: JsField*) = new JsObject(Map(members: _*))
+  val empty = JsObject(TreeMap.empty[String, JsValue])
+  def apply(members: JsField*) = new JsObject(TreeMap(members: _*))
   @deprecated("Use JsObject(JsValue*) instead", "1.3.0")
-  def apply(members: List[JsField]) = new JsObject(Map(members: _*))
+  def apply(members: List[JsField]) = apply(members: _*)
 }
 
 /**
diff --git a/src/main/scala/spray/json/JsonParser.scala b/src/main/scala/spray/json/JsonParser.scala
index 71c4c119..fb94b9c3 100644
--- a/src/main/scala/spray/json/JsonParser.scala
+++ b/src/main/scala/spray/json/JsonParser.scala
@@ -18,9 +18,11 @@ package spray.json
 
 import scala.annotation.{switch, tailrec}
 import java.lang.{StringBuilder => JStringBuilder}
-import java.nio.{CharBuffer, ByteBuffer}
+import java.nio.{ByteBuffer, CharBuffer}
 import java.nio.charset.Charset
 
+import scala.collection.immutable.TreeMap
+
 /**
  * Fast, no-dependency parser for JSON as defined by http://tools.ietf.org/html/rfc4627.
  */
@@ -86,8 +88,7 @@ class JsonParser(input: ParserInput) {
         val nextMap = map.updated(key, jsValue)
         if (ws(',')) members(nextMap) else nextMap
       }
-      var map = Map.empty[String, JsValue]
-      map = members(map)
+      val map = members(TreeMap.empty[String, JsValue])
       require('}')
       JsObject(map)
     } else {