diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
index 760cf687..7ab4a744 100644
--- a/npm-shrinkwrap.json
+++ b/npm-shrinkwrap.json
@@ -1356,6 +1356,12 @@
       "integrity": "sha512-1OzrNb4RuAzIT7wHSsgZRlMBlNsJl+do6UblR7JMW4oB7bbR+uBEYtUh7gEc/jM84GGilh68lSOokyM/zNUlBA==",
       "dev": true
     },
+    "@types/sinon": {
+      "version": "7.5.1",
+      "resolved": "https://registry.npmjs.org/@types/sinon/-/sinon-7.5.1.tgz",
+      "integrity": "sha512-EZQUP3hSZQyTQRfiLqelC9NMWd1kqLcmQE0dMiklxBkgi84T+cHOhnKpgk4NnOWpGX863yE6+IaGnOXUNFqDnQ==",
+      "dev": true
+    },
     "@types/source-list-map": {
       "version": "0.1.2",
       "resolved": "https://registry.npmjs.org/@types/source-list-map/-/source-list-map-0.1.2.tgz",
diff --git a/package.json b/package.json
index d851cbd8..30b6417a 100644
--- a/package.json
+++ b/package.json
@@ -102,6 +102,7 @@
     "@types/react-dom": "^16.8.4",
     "@types/request": "^2.48.4",
     "@types/semver": "^6.2.0",
+    "@types/sinon": "^7.5.1",
     "@types/tmp": "^0.1.0",
     "@types/webpack-node-externals": "^1.7.0",
     "babel-loader": "^8.0.4",
diff --git a/tests/gui/os/window-progress.spec.js b/tests/gui/os/window-progress.spec.js
deleted file mode 100644
index 9893a6fc..00000000
--- a/tests/gui/os/window-progress.spec.js
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * Copyright 2016 balena.io
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-'use strict'
-
-const m = require('mochainon')
-// eslint-disable-next-line node/no-missing-require
-const windowProgress = require('../../../lib/gui/app/os/window-progress')
-
-describe('Browser: WindowProgress', function () {
-  describe('windowProgress', function () {
-    describe('given a stubbed current window', function () {
-      beforeEach(function () {
-        this.setProgressBarSpy = m.sinon.spy()
-        this.setTitleSpy = m.sinon.spy()
-
-        windowProgress.currentWindow = {
-          setProgressBar: this.setProgressBarSpy,
-          setTitle: this.setTitleSpy
-        }
-
-        this.state = {
-          flashing: 1,
-          verifying: 0,
-          successful: 0,
-          failed: 0,
-          percentage: 85,
-          speed: 100
-        }
-      })
-
-      describe('.set()', function () {
-        it('should translate 0-100 percentages to 0-1 ranges', function () {
-          windowProgress.set(this.state)
-          m.chai.expect(this.setProgressBarSpy).to.have.been.calledWith(0.85)
-        })
-
-        it('should set 0 given 0', function () {
-          this.state.percentage = 0
-          windowProgress.set(this.state)
-          m.chai.expect(this.setProgressBarSpy).to.have.been.calledWith(0)
-        })
-
-        it('should set 1 given 100', function () {
-          this.state.percentage = 100
-          windowProgress.set(this.state)
-          m.chai.expect(this.setProgressBarSpy).to.have.been.calledWith(1)
-        })
-
-        it('should throw if given a percentage higher than 100', function () {
-          this.state.percentage = 101
-          const state = this.state
-          m.chai.expect(function () {
-            windowProgress.set(state)
-          }).to.throw('Invalid percentage: 101')
-        })
-
-        it('should throw if given a percentage less than 0', function () {
-          this.state.percentage = -1
-          const state = this.state
-          m.chai.expect(function () {
-            windowProgress.set(state)
-          }).to.throw('Invalid percentage: -1')
-        })
-
-        it('should set the flashing title', function () {
-          windowProgress.set(this.state)
-          m.chai.expect(this.setTitleSpy).to.have.been.calledWith(' \u2013 85% Flashing')
-        })
-
-        it('should set the verifying title', function () {
-          this.state.flashing = 0
-          this.state.verifying = 1
-          windowProgress.set(this.state)
-          m.chai.expect(this.setTitleSpy).to.have.been.calledWith(' \u2013 85% Validating')
-        })
-
-        it('should set the starting title', function () {
-          this.state.percentage = 0
-          this.state.speed = 0
-          windowProgress.set(this.state)
-          m.chai.expect(this.setTitleSpy).to.have.been.calledWith(' \u2013 Starting...')
-        })
-
-        it('should set the finishing title', function () {
-          this.state.percentage = 100
-          windowProgress.set(this.state)
-          m.chai.expect(this.setTitleSpy).to.have.been.calledWith(' \u2013 Finishing...')
-        })
-      })
-
-      describe('.clear()', function () {
-        it('should set -1', function () {
-          windowProgress.clear()
-          m.chai.expect(this.setProgressBarSpy).to.have.been.calledWith(-1)
-        })
-
-        it('should clear the window title', function () {
-          windowProgress.clear()
-          m.chai.expect(this.setTitleSpy).to.have.been.calledWith('')
-        })
-      })
-    })
-  })
-})
diff --git a/tests/gui/os/window-progress.spec.ts b/tests/gui/os/window-progress.spec.ts
new file mode 100644
index 00000000..08df5854
--- /dev/null
+++ b/tests/gui/os/window-progress.spec.ts
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2016 balena.io
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { expect } from 'chai';
+import { assert, spy } from 'sinon';
+
+import * as windowProgress from '../../../lib/gui/app/os/window-progress';
+
+describe('Browser: WindowProgress', function() {
+	describe('windowProgress', function() {
+		describe('given a stubbed current window', function() {
+			beforeEach(function() {
+				this.setProgressBarSpy = spy();
+				this.setTitleSpy = spy();
+
+				windowProgress.currentWindow.setProgressBar = this.setProgressBarSpy;
+				windowProgress.currentWindow.setTitle = this.setTitleSpy;
+
+				this.state = {
+					flashing: 1,
+					verifying: 0,
+					successful: 0,
+					failed: 0,
+					percentage: 85,
+					speed: 100,
+				};
+			});
+
+			describe('.set()', function() {
+				it('should translate 0-100 percentages to 0-1 ranges', function() {
+					windowProgress.set(this.state);
+					assert.calledWith(this.setProgressBarSpy, 0.85);
+				});
+
+				it('should set 0 given 0', function() {
+					this.state.percentage = 0;
+					windowProgress.set(this.state);
+					assert.calledWith(this.setProgressBarSpy, 0);
+				});
+
+				it('should set 1 given 100', function() {
+					this.state.percentage = 100;
+					windowProgress.set(this.state);
+					assert.calledWith(this.setProgressBarSpy, 1);
+				});
+
+				it('should throw if given a percentage higher than 100', function() {
+					this.state.percentage = 101;
+					const state = this.state;
+					expect(function() {
+						windowProgress.set(state);
+					}).to.throw('Invalid percentage: 101');
+				});
+
+				it('should throw if given a percentage less than 0', function() {
+					this.state.percentage = -1;
+					const state = this.state;
+					expect(function() {
+						windowProgress.set(state);
+					}).to.throw('Invalid percentage: -1');
+				});
+
+				it('should set the flashing title', function() {
+					windowProgress.set(this.state);
+					assert.calledWith(this.setTitleSpy, ' – 85% Flashing');
+				});
+
+				it('should set the verifying title', function() {
+					this.state.flashing = 0;
+					this.state.verifying = 1;
+					windowProgress.set(this.state);
+					assert.calledWith(this.setTitleSpy, ' – 85% Validating');
+				});
+
+				it('should set the starting title', function() {
+					this.state.percentage = 0;
+					this.state.speed = 0;
+					windowProgress.set(this.state);
+					assert.calledWith(this.setTitleSpy, ' – Starting...');
+				});
+
+				it('should set the finishing title', function() {
+					this.state.percentage = 100;
+					windowProgress.set(this.state);
+					assert.calledWith(this.setTitleSpy, ' – Finishing...');
+				});
+			});
+
+			describe('.clear()', function() {
+				it('should set -1', function() {
+					windowProgress.clear();
+					assert.calledWith(this.setProgressBarSpy, -1);
+				});
+
+				it('should clear the window title', function() {
+					windowProgress.clear();
+					assert.calledWith(this.setTitleSpy, '');
+				});
+			});
+		});
+	});
+});