diff --git a/.gitignore b/.gitignore
index 737dad19..53cb59c2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ dist/
 openpgp.store/
 doc/
 browserify-cache*.json
+.nyc_output/
diff --git a/Gruntfile.js b/Gruntfile.js
index 7044ff9e..b4f19f50 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -103,6 +103,23 @@ module.exports = function(grunt) {
         }
       }
     },
+    nyc: {
+      cover: {
+        options: {
+          include: ['dist/**'],
+          reporter: ['text-summary'],
+          reportDir: 'coverage'
+        },
+        cmd: false,
+        args: ['grunt', 'mochaTest'],
+        sourceMap: true
+      },
+      report: {
+        options: {
+          reporter: 'text'
+        }
+      }
+    },
     replace: {
       openpgp: {
         src: ['dist/openpgp.js'],
@@ -200,15 +217,6 @@ module.exports = function(grunt) {
         }
       }
     },
-    mocha_istanbul: {
-      coverage: {
-        src: 'test',
-        options: {
-          root: '.',
-          timeout: 240000
-        }
-      }
-    },
     mochaTest: {
       unittests: {
         options: {
@@ -285,12 +293,12 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('grunt-jsbeautifier');
   grunt.loadNpmTasks('grunt-jsdoc');
   grunt.loadNpmTasks('gruntify-eslint');
-  grunt.loadNpmTasks('grunt-mocha-istanbul');
   grunt.loadNpmTasks('grunt-mocha-test');
   grunt.loadNpmTasks('grunt-contrib-copy');
   grunt.loadNpmTasks('grunt-contrib-clean');
   grunt.loadNpmTasks('grunt-contrib-connect');
   grunt.loadNpmTasks('grunt-contrib-watch');
+  grunt.loadNpmTasks('grunt-simple-nyc');
 
   grunt.registerTask('set_version', function() {
     if (!version) {
@@ -340,6 +348,6 @@ module.exports = function(grunt) {
   grunt.registerTask('default', ['build']);
   // Test/Dev tasks
   grunt.registerTask('test', ['eslint', 'mochaTest']);
-  grunt.registerTask('coverage', ['mocha_istanbul:coverage']);
+  grunt.registerTask('coverage', ['nyc']);
   grunt.registerTask('browsertest', ['build', 'browserify:unittests', 'copy:browsertest', 'connect:test', 'watch']);
 };
diff --git a/package.json b/package.json
index 9ecd51b6..c8c74b25 100644
--- a/package.json
+++ b/package.json
@@ -60,13 +60,13 @@
     "grunt-header": "^1.1.0",
     "grunt-jsbeautifier": "^0.2.13",
     "grunt-jsdoc": "^2.2.1",
-    "grunt-mocha-istanbul": "^5.0.2",
     "grunt-mocha-test": "^0.13.3",
+    "grunt-simple-nyc": "^3.0.1",
     "grunt-terser": "^0.1.0",
     "grunt-text-replace": "~0.4.0",
     "gruntify-eslint": "^4.0.0",
-    "istanbul": "^0.4.5",
     "mocha": "^5.0.0",
+    "nyc": "^14.1.1",
     "sinon": "^4.3.0",
     "text-encoding-utf-8": "^1.0.2",
     "whatwg-fetch": "^2.0.3",