diff --git a/querystring/build.js b/querystring/build.js
index 55474392..54a6e051 100644
--- a/querystring/build.js
+++ b/querystring/build.js
@@ -1,12 +1,15 @@
 "use strict"
 
-module.exports = function(object) {
+module.exports = function(object, dataKeys) {
 	if (Object.prototype.toString.call(object) !== "[object Object]") return ""
 
 	var args = []
-	for (var key in object) {
+	dataKeys = dataKeys || Object.keys(object)
+	for (var i = 0; i < dataKeys.length; i++) {
+		var key = dataKeys[i]
 		destructure(key, object[key])
 	}
+	
 	return args.join("&")
 
 	function destructure(key, value) {
diff --git a/request/request.js b/request/request.js
index 304673fc..52f4ace8 100644
--- a/request/request.js
+++ b/request/request.js
@@ -7,6 +7,7 @@ module.exports = function($window, Promise) {
 
 	var oncompletion
 	function setCompletionCallback(callback) {oncompletion = callback}
+	
 	function finalizer() {
 		var count = 0
 		function complete() {if (--count === 0 && typeof oncompletion === "function") oncompletion()}
@@ -48,9 +49,10 @@ module.exports = function($window, Promise) {
 			if (typeof args.deserialize !== "function") args.deserialize = deserialize
 			if (typeof args.extract !== "function") args.extract = extract
 
-			args.url = interpolate(args.url, args.data)
-			if (useBody) args.data = args.serialize(args.data)
-			else args.url = assemble(args.url, args.data)
+			var dataKeys = args.data && Object.keys(args.data)
+			args.url = interpolate(args.url, args.data, dataKeys)
+			if (useBody) args.data = args.serialize(args.data, dataKeys)
+			else args.url = assemble(args.url, args.data, dataKeys)
 
 			var xhr = new $window.XMLHttpRequest()
 			xhr.open(args.method, args.url, typeof args.async === "boolean" ? args.async : true, typeof args.user === "string" ? args.user : undefined, typeof args.password === "string" ? args.password : undefined)
@@ -122,7 +124,7 @@ module.exports = function($window, Promise) {
 		return args.background === true? promise : finalize(promise)
 	}
 
-	function interpolate(url, data) {
+	function interpolate(url, data, dataKeys) {
 		if (data == null) return url
 
 		var tokens = url.match(/:[^\/]+/gi) || []
@@ -130,14 +132,20 @@ module.exports = function($window, Promise) {
 			var key = tokens[i].slice(1)
 			if (data[key] != null) {
 				url = url.replace(tokens[i], data[key])
-				delete data[key]
+			
+				if (Array.isArray(dataKeys)) {
+					var keyIndex = dataKeys.indexOf(key)
+					if (keyIndex > -1) {
+						dataKeys.splice(keyIndex)
+					}
+				}
 			}
 		}
 		return url
 	}
 
-	function assemble(url, data) {
-		var querystring = buildQueryString(data)
+	function assemble(url, data, dataKeys) {
+		var querystring = buildQueryString(data, dataKeys)
 		if (querystring !== "") {
 			var prefix = url.indexOf("?") < 0 ? "?" : "&"
 			url += prefix + querystring
diff --git a/request/tests/test-request.js b/request/tests/test-request.js
index a9fce1dd..70a66779 100644
--- a/request/tests/test-request.js
+++ b/request/tests/test-request.js
@@ -380,6 +380,18 @@ o.spec("xhr", function() {
 				o(xhr.getRequestHeader("Accept")).equals("application/json, text/*")
 			}
 		})
+		o("data maintains after interpolate", function() {
+			mock.$defineRoutes({
+				"PUT /items/:x": function() {
+					return {status: 200, responseText: ""}
+				}
+			})
+			var data = {x: 1, y: 2}
+			var dataCopy = Object.assign({}, data);
+			xhr({method: "PUT", url: "/items/:x", data})
+
+			o(data).deepEquals(dataCopy)
+		})
 	})
 	o.spec("failure", function() {
 		o("rejects on server error", function(done) {