diff --git a/lib/utils.js b/lib/utils.js
index 7c828fb4..67496a71 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -428,9 +428,9 @@ exports.prepareContent = function(name, inputData, isBinary, isOptimizedBinarySt
     var promise = external.Promise.resolve(inputData).then(function(data) {
         
         
-        var isBlob = data instanceof Blob || ['[object File]', '[object Blob]'].indexOf(Object.prototype.toString.call(data)) !== -1;
+        var isBlob = support.blob && (data instanceof Blob || ['[object File]', '[object Blob]'].indexOf(Object.prototype.toString.call(data)) !== -1);
 
-        if (support.blob && isBlob && typeof FileReader !== "undefined") {
+        if (isBlob && typeof FileReader !== "undefined") {
             return new external.Promise(function (resolve, reject) {
                 var reader = new FileReader();
 
diff --git a/test/helpers/node-test-utils.js b/test/helpers/node-test-utils.js
index 69fbb769..6eb3a6f3 100644
--- a/test/helpers/node-test-utils.js
+++ b/test/helpers/node-test-utils.js
@@ -12,6 +12,12 @@ global.JSZipTestUtils.loadZipFile = function(name, callback) {
 };
 process.on('uncaughtException', function(err) {
       console.log('uncaughtException: ' + err, err.stack);
+      process.exit(1);
+});
+
+process.on('unhandledRejection', function(err) {
+      console.log('unhandledRejection: ' + err, err.stack);
+      process.exit(1);
 });