diff --git a/src/urlMatcherFactory.js b/src/urlMatcherFactory.js
index a4b4bd62b..0f0e603d5 100644
--- a/src/urlMatcherFactory.js
+++ b/src/urlMatcherFactory.js
@@ -163,7 +163,7 @@ UrlMatcher.prototype.exec = function (path, searchParams) {
 
   if (nPath !== m.length - 1) throw new Error("Unbalanced capture group in route '" + this.source + "'");
 
-  for (i=0; i<nPath; i++) values[params[i]] = decodeURIComponent(m[i+1]);
+  for (i=0; i<nPath; i++) values[params[i]] = m[i+1];
   for (/**/; i<nTotal; i++) values[params[i]] = searchParams[params[i]];
 
   return values;
@@ -202,7 +202,7 @@ UrlMatcher.prototype.format = function (values) {
   for (i=0; i<nPath; i++) {
     value = values[params[i]];
     // TODO: Maybe we should throw on null here? It's not really good style to use '' and null interchangeabley
-    if (value != null) result += value;
+    if (value != null) result += encodeURIComponent(value);
     result += segments[i+1];
   }
   for (/**/; i<nTotal; i++) {
diff --git a/test/urlMatcherFactorySpec.js b/test/urlMatcherFactorySpec.js
index 3d0f44803..a88b713c8 100644
--- a/test/urlMatcherFactorySpec.js
+++ b/test/urlMatcherFactorySpec.js
@@ -40,6 +40,10 @@ describe("UrlMatcher", function () {
       .toBeNull();
   });
 
+  it(".exec() treats the URL as already decoded and does not decode it further", function () {
+    expect(new UrlMatcher('/users/:id').exec('/users/100%25', {})).toEqual({ id: '100%25'});
+  });
+
   it('.exec() throws on unbalanced capture list', function () {
     var shouldThrow = {
       "/url/{matchedParam:([a-z]+)}/child/{childParam}": '/url/someword/child/childParam',
@@ -69,6 +73,10 @@ describe("UrlMatcher", function () {
       .toEqual('/users/123/details/default/444?from=1970');
   });
 
+  it(".format() encodes URL parameters", function () {
+    expect(new UrlMatcher('/users/:id').format({ id:'100%'})).toEqual('/users/100%25');
+  });
+
   it(".concat() concatenates matchers", function () {
     var matcher = new UrlMatcher('/users/:id/details/{type}?from').concat('/{repeat:[0-9]+}?to');
     var params = matcher.parameters();