diff --git a/bower.json b/bower.json
index c816ea0..f5b1753 100644
--- a/bower.json
+++ b/bower.json
@@ -1,6 +1,6 @@
 {
   "name": "aurelia-path",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "description": "Utilities for path manipulation.",
   "keywords": [
     "aurelia",
diff --git a/dist/aurelia-path.d.ts b/dist/aurelia-path.d.ts
index 0061e4f..7b2a443 100644
--- a/dist/aurelia-path.d.ts
+++ b/dist/aurelia-path.d.ts
@@ -24,7 +24,7 @@ export declare function join(path1: string, path2: string): string;
 * @param traditional Boolean Use the old URI template standard (RFC6570)
 * @returns The generated query string, excluding leading '?'.
 */
-export declare function buildQueryString(params: Object, traditional: Boolean): string;
+export declare function buildQueryString(params: Object, traditional?: Boolean): string;
 
 /**
 * Parse a query string.
diff --git a/dist/aurelia-path.js b/dist/aurelia-path.js
index 051d86c..a9141aa 100644
--- a/dist/aurelia-path.js
+++ b/dist/aurelia-path.js
@@ -117,7 +117,7 @@ let encodeKey = k => encode(k).replace('%24', '$');
 * @param traditional Boolean Use the old URI template standard (RFC6570)
 * @return Array with serialized parameter(s)
 */
-function buildParam(key: string, value: any, traditional: boolean): Array<string> {
+function buildParam(key: string, value: any, traditional?: boolean): Array<string> {
   let result = [];
   if (value === null || value === undefined) {
     return result;
@@ -148,7 +148,7 @@ function buildParam(key: string, value: any, traditional: boolean): Array<string
 * @param traditional Boolean Use the old URI template standard (RFC6570)
 * @returns The generated query string, excluding leading '?'.
 */
-export function buildQueryString(params: Object, traditional: Boolean): string {
+export function buildQueryString(params: Object, traditional?: Boolean): string {
   let pairs = [];
   let keys = Object.keys(params || {}).sort();
   for (let i = 0, len = keys.length; i < len; i++) {
diff --git a/doc/CHANGELOG.md b/doc/CHANGELOG.md
index 84b24ff..560b3f5 100644
--- a/doc/CHANGELOG.md
+++ b/doc/CHANGELOG.md
@@ -1,3 +1,13 @@
+<a name="1.1.1"></a>
+## [1.1.1](https://github.com/aurelia/path/compare/1.1.0...v1.1.1) (2016-09-23)
+
+
+### Bug Fixes
+
+* **index:** ensure new traditional param is marked as optional ([fc600e5](https://github.com/aurelia/path/commit/fc600e5))
+
+
+
 <a name="1.1.0"></a>
 # [1.1.0](https://github.com/aurelia/path/compare/1.0.0...v1.1.0) (2016-09-22)
 
diff --git a/doc/api.json b/doc/api.json
index 65ffbac..64e7286 100644
--- a/doc/api.json
+++ b/doc/api.json
@@ -1 +1 @@
-{"name":"aurelia-path","children":[{"id":10,"name":"buildQueryString","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":11,"name":"buildQueryString","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Generate a query string from an object.","returns":"The generated query string, excluding leading '?'.\n"},"parameters":[{"id":12,"name":"params","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"Object containing the keys and values to be used."},"type":{"type":"reference","name":"Object"}},{"id":13,"name":"traditional","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"Boolean Use the old URI template standard (RFC6570)"},"type":{"type":"reference","name":"Boolean"}}],"type":{"type":"instrinct","name":"string"}}]},{"id":6,"name":"join","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":7,"name":"join","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Joins two paths.","returns":"The joined path.\n"},"parameters":[{"id":8,"name":"path1","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The first path."},"type":{"type":"instrinct","name":"string"}},{"id":9,"name":"path2","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The second path."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"instrinct","name":"string"}}]},{"id":14,"name":"parseQueryString","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":15,"name":"parseQueryString","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Parse a query string.","returns":"Object with keys and values mapped from the query string.\n"},"parameters":[{"id":16,"name":"queryString","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The query string to parse."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"reference","name":"Object"}}]},{"id":2,"name":"relativeToFile","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":3,"name":"relativeToFile","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Calculates a path relative to a file.","returns":"The calculated path.\n"},"parameters":[{"id":4,"name":"name","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The relative path."},"type":{"type":"instrinct","name":"string"}},{"id":5,"name":"file","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The file path."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"instrinct","name":"string"}}]}],"groups":[{"title":"Functions","kind":64,"children":[10,6,14,2]}]}
\ No newline at end of file
+{"name":"aurelia-path","children":[{"id":10,"name":"buildQueryString","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":11,"name":"buildQueryString","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Generate a query string from an object.","returns":"The generated query string, excluding leading '?'.\n"},"parameters":[{"id":12,"name":"params","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"Object containing the keys and values to be used."},"type":{"type":"reference","name":"Object"}},{"id":13,"name":"traditional","kind":32768,"kindString":"Parameter","flags":{"isOptional":true},"comment":{"text":"Boolean Use the old URI template standard (RFC6570)"},"type":{"type":"reference","name":"Boolean"}}],"type":{"type":"instrinct","name":"string"}}]},{"id":6,"name":"join","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":7,"name":"join","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Joins two paths.","returns":"The joined path.\n"},"parameters":[{"id":8,"name":"path1","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The first path."},"type":{"type":"instrinct","name":"string"}},{"id":9,"name":"path2","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The second path."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"instrinct","name":"string"}}]},{"id":14,"name":"parseQueryString","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":15,"name":"parseQueryString","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Parse a query string.","returns":"Object with keys and values mapped from the query string.\n"},"parameters":[{"id":16,"name":"queryString","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The query string to parse."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"reference","name":"Object"}}]},{"id":2,"name":"relativeToFile","kind":64,"kindString":"Function","flags":{"isExported":true},"signatures":[{"id":3,"name":"relativeToFile","kind":4096,"kindString":"Call signature","flags":{},"comment":{"shortText":"Calculates a path relative to a file.","returns":"The calculated path.\n"},"parameters":[{"id":4,"name":"name","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The relative path."},"type":{"type":"instrinct","name":"string"}},{"id":5,"name":"file","kind":32768,"kindString":"Parameter","flags":{},"comment":{"text":"The file path."},"type":{"type":"instrinct","name":"string"}}],"type":{"type":"instrinct","name":"string"}}]}],"groups":[{"title":"Functions","kind":64,"children":[10,6,14,2]}]}
\ No newline at end of file
diff --git a/package.json b/package.json
index 4c8febb..24935cc 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "aurelia-path",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "description": "Utilities for path manipulation.",
   "keywords": [
     "aurelia",