diff --git a/urijs/URIjs-tests.ts b/urijs/URIjs-tests.ts
index 3501a6efc..0f529fe4a 100644
--- a/urijs/URIjs-tests.ts
+++ b/urijs/URIjs-tests.ts
@@ -37,4 +37,9 @@ var uri: uri.URI = $('a').uri();
 
 URI('http://example.org/foo/hello.html').segment('bar');
 URI('http://example.org/foo/hello.html').segment(0, 'bar');
-URI('http://example.org/foo/hello.html').segment(['foo', 'bar', 'foobar.html']);
\ No newline at end of file
+URI('http://example.org/foo/hello.html').segment(['foo', 'bar', 'foobar.html']);
+
+var withDuplicates = URI("?bar=1&bar=1")
+  .duplicateQueryParameters(true)
+  .normalizeQuery()
+  .toString();
\ No newline at end of file
diff --git a/urijs/URIjs.d.ts b/urijs/URIjs.d.ts
index a41e06cbf..3bd4ba366 100644
--- a/urijs/URIjs.d.ts
+++ b/urijs/URIjs.d.ts
@@ -27,6 +27,8 @@ declare module uri {
         domain(): string;
         domain(domain: boolean): string;
         domain(domain: string): URI;
+        
+        duplicateQueryParameters(val: boolean): URI;
 
         equals(): boolean;
         equals(url: string): boolean;