diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..4106df6
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,10 @@
+export function getDrives(callback: (err: any, drivers: Driver[]) => void): void;
+
+export interface Driver {
+  filesystem: string;
+  blocks: number;
+  used: number;
+  available: number;
+  capacity: string;
+  mounted: string;
+}
diff --git a/lib/diskinfo.js b/lib/diskinfo.js
index 3816565..11c4842 100644
--- a/lib/diskinfo.js
+++ b/lib/diskinfo.js
@@ -9,7 +9,6 @@
 
 var exec = require('child_process').exec;
 var os = require('os');
-var aDrives = [];
 
 /**
 *	Returns an array of drives or calls callback 
@@ -18,7 +17,7 @@ var aDrives = [];
 *						the array of drives, set null if no callback 
 */
 exports.getDrives = function(callback) {
-	
+	var aDrives = [];
 	switch (os.platform().toLowerCase()) {
         case 'win32':