diff --git a/gulp-sort/gulp-sort-tests.ts b/gulp-sort/gulp-sort-tests.ts
index 0dd260f66..12685c085 100644
--- a/gulp-sort/gulp-sort-tests.ts
+++ b/gulp-sort/gulp-sort-tests.ts
@@ -5,6 +5,7 @@
 
 import gulp = require('gulp');
 import sort = require('gulp-sort');
+import gulpUtil = require('gulp-util');
 
 // default sort
 gulp.src('./src/js/**/*.js')
@@ -38,7 +39,7 @@ gulp.src('./src/js/**/*.js')
     }))
     .pipe(gulp.dest('./build/js'));
 	
-function customComparator(file1, file2) {
+function customComparator(file1: gulpUtil.File, file2: gulpUtil.File) {
     if (file1.path.indexOf('build') > -1) {
         return 1;
     }
diff --git a/gulp-sort/gulp-sort.d.ts b/gulp-sort/gulp-sort.d.ts
index 7289c1f51..c06b9c3e0 100644
--- a/gulp-sort/gulp-sort.d.ts
+++ b/gulp-sort/gulp-sort.d.ts
@@ -21,7 +21,7 @@ declare module 'gulp-sort' {
 		 */
 		comparator?: IComparatorFunction;
 		/** Whether to sort in ascending order, default is true */
-		asc?;
+		asc?: boolean;
 	}
 	
 	interface IComparatorFunction {