diff --git a/types/grunt/grunt-tests.ts b/types/grunt/grunt-tests.ts
index 5dd6550582..94eb12a46f 100644
--- a/types/grunt/grunt-tests.ts
+++ b/types/grunt/grunt-tests.ts
@@ -1,6 +1,6 @@
 
 
-// Official code sample from 
+// Official code sample from
 // http://gruntjs.com/getting-started#an-example-gruntfile
 
 interface MyTaskData {
@@ -12,7 +12,7 @@ interface MyOptions {
     repeat: number;
 }
 
-// exports should work same as module.exports 
+// exports should work same as module.exports
 exports = (grunt: IGrunt) => {
 
     // Project configuration.
@@ -126,4 +126,10 @@ exports.exports = function(grunt: IGrunt) {
         });
     });
 
-};
\ No newline at end of file
+};
+
+
+let myTest = function (grunt: IGrunt) {
+    grunt.file.expand(['*.ts']);
+    grunt.file.expand('*.ts');
+}
diff --git a/types/grunt/index.d.ts b/types/grunt/index.d.ts
index 34e5b7e3cb..5187e5e965 100644
--- a/types/grunt/index.d.ts
+++ b/types/grunt/index.d.ts
@@ -445,7 +445,7 @@ declare namespace grunt {
              * File paths are relative to the Gruntfile unless the current working directory is changed with
              * grunt.file.setBase or the --base command-line option.
              */
-            expand(patterns: string[]): string[];
+            expand(patterns: string | string[]): string[];
             expand(options: IFilesConfig, patterns: string[]): string[];
 
             /**