diff --git a/index.d.ts b/index.d.ts
index 4fc599d..2a10a7a 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -4,21 +4,21 @@
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 /** Attempts to read filename and parse */
-export declare function readFile(filename: string, opts?: IParsingOptions): IWorkBook;
+export function readFile(filename: string, opts?: IParsingOptions): IWorkBook;
 /** Attempts to parse data */
-export declare function read(data: any, opts?: IParsingOptions): IWorkBook;
+export function read(data: any, opts?: IParsingOptions): IWorkBook;
 /** Attempts to write workbook data to filename */
-export declare function writeFile(data: IWorkBook, filename: string, opts?: IWritingOptions): any;
+export function writeFile(data: IWorkBook, filename: string, opts?: IWritingOptions): any;
 /** Attempts to write the workbook data */
-export declare function write(data: IWorkBook, opts?: IWritingOptions): any;
+export function write(data: IWorkBook, opts?: IWritingOptions): any;
 
-export declare var utils: IUtils;
+export const utils: IUtils;
 
 export interface IProperties {
-    LastAuthor?: string
+    LastAuthor?: string;
     Author?: string;
     CreatedDate?: Date;
-    ModifiedDate?: Date
+    ModifiedDate?: Date;
     Application?: string;
     AppVersion?: string;
     Company?: string;
diff --git a/xlsx-tests.ts b/xlsx-tests.ts
index 6051ce3..83d0b19 100644
--- a/xlsx-tests.ts
+++ b/xlsx-tests.ts
@@ -1,17 +1,17 @@
 import xlsx = require('xlsx');
 
-var options: xlsx.IParsingOptions = {
+const options: xlsx.IParsingOptions = {
     cellDates: true
 };
 
-var workbook = xlsx.readFile('test.xlsx', options);
-var otherworkbook = xlsx.readFile('test.xlsx', {type: 'file'});
+const workbook = xlsx.readFile('test.xlsx', options);
+const otherworkbook = xlsx.readFile('test.xlsx', {type: 'file'});
 
 console.log(workbook.Props.Author);
 
-var firstsheet: string = workbook.SheetNames[0];
+const firstsheet: string = workbook.SheetNames[0];
 
-var firstworksheet = workbook.Sheets[firstsheet];
+const firstworksheet = workbook.Sheets[firstsheet];
 
 console.log(firstworksheet["A1"]);
 
@@ -20,6 +20,6 @@ interface tester {
     age: number;
 }
 
-var jsonvalues: tester[] = xlsx.utils.sheet_to_json<tester>(firstworksheet);
-var csv = xlsx.utils.sheet_to_csv(firstworksheet);
-var formulae = xlsx.utils.sheet_to_formulae(firstworksheet);
+const jsonvalues: tester[] = xlsx.utils.sheet_to_json<tester>(firstworksheet);
+const csv = xlsx.utils.sheet_to_csv(firstworksheet);
+const formulae = xlsx.utils.sheet_to_formulae(firstworksheet);