diff --git a/zip.js/zip.js-tests.ts b/zip.js/zip.js-tests.ts
index bacaf1cd6..fa085ca38 100644
--- a/zip.js/zip.js-tests.ts
+++ b/zip.js/zip.js-tests.ts
@@ -1,18 +1,18 @@
 // create the blob object storing the data to compress
-var blob = new Blob([ "Lorem ipsum dolor sit amet, consectetuer adipiscing elit..." ], {
+var blob: Blob = new Blob([ "Lorem ipsum dolor sit amet, consectetuer adipiscing elit..." ], {
   type : "text/plain"
 });
 // creates a zip storing the file "lorem.txt" with blob as data
 // the zip will be stored into a Blob object (zippedBlob)
-zipBlob("lorem.txt", blob, function(zippedBlob) {
+zipBlob("lorem.txt", blob, function(zippedBlob: Blob) {
   // unzip the first file from zipped data stored in zippedBlob
-  unzipBlob(zippedBlob, function(unzippedBlob) {
+  unzipBlob(zippedBlob, function(unzippedBlob: Blob) {
     // logs the uncompressed Blob
     console.log(unzippedBlob);
   });
 });
 
-function zipBlob(filename, blob, callback) {
+function zipBlob(filename: string, blob: Blob, callback: (blob: Blob) => void) {
   // use a zip.BlobWriter object to write zipped data into a Blob object
   zip.createWriter(new zip.BlobWriter("application/zip"), function(zipWriter) {
     // use a BlobReader object to read the data stored into blob variable
@@ -20,24 +20,24 @@ function zipBlob(filename, blob, callback) {
       // close the writer and calls callback function
       zipWriter.close(callback);
     });
-  }, onerror);
+  }, theErrorHandler);
 }
 
-function unzipBlob(blob, callback) {
+function unzipBlob(blob: Blob, callback: (unzippedBlob: Blob) => void) {
   // use a zip.BlobReader object to read zipped data stored into blob variable
   zip.createReader(new zip.BlobReader(blob), function(zipReader) {
     // get entries from the zip file
-    zipReader.getEntries(function(entries) {
+    zipReader.getEntries(function(entries: zip.Entry[]) {
       // get data from the first file
-      entries[0].getData(new zip.BlobWriter("text/plain"), function(data) {
+      entries[0].getData(new zip.BlobWriter("text/plain"), function(data: Blob) {
         // close the reader and calls callback function with uncompressed data as parameter
         zipReader.close();
         callback(data);
       });
     });
-  }, onerror);
+  }, theErrorHandler);
 }
 
-function onerror(message) {
+function theErrorHandler(message) {
   console.error(message);
 }
\ No newline at end of file