diff --git a/lib/gui/models/store.js b/lib/gui/models/store.js
index 2914407f..bb4193e0 100644
--- a/lib/gui/models/store.js
+++ b/lib/gui/models/store.js
@@ -26,6 +26,7 @@ const supportedFormats = require('../../shared/supported-formats');
 const errors = require('../../shared/errors');
 const release = require('../../shared/release');
 const fileExtensions = require('../../shared/file-extensions');
+const utils = require('../../shared/utils');
 const packageJSON = require('../../../package.json');
 
 /**
@@ -203,7 +204,7 @@ const storeReducer = (state = DEFAULT_STATE, action) => {
         });
       }
 
-      if (!_.isNumber(action.data.percentage)) {
+      if (!utils.isValidPercentage(action.data.percentage)) {
         throw errors.createError({
           title: `Invalid state percentage: ${action.data.percentage}`
         });
diff --git a/tests/gui/models/flash-state.spec.js b/tests/gui/models/flash-state.spec.js
index 39df0340..43753924 100644
--- a/tests/gui/models/flash-state.spec.js
+++ b/tests/gui/models/flash-state.spec.js
@@ -143,6 +143,30 @@ describe('Browser: flashState', function() {
         }).to.throw('Invalid state percentage: 50');
       });
 
+      it('should throw if percentage is outside maximum bound', function() {
+        flashState.setFlashingFlag();
+        m.chai.expect(function() {
+          flashState.setProgressState({
+            type: 'write',
+            percentage: 101,
+            eta: 15,
+            speed: 0
+          });
+        }).to.throw('Invalid state percentage: 101');
+      });
+
+      it('should throw if percentage is outside minimum bound', function() {
+        flashState.setFlashingFlag();
+        m.chai.expect(function() {
+          flashState.setProgressState({
+            type: 'write',
+            percentage: -1,
+            eta: 15,
+            speed: 0
+          });
+        }).to.throw('Invalid state percentage: -1');
+      });
+
       it('should throw if eta is missing', function() {
         flashState.setFlashingFlag();
         m.chai.expect(function() {