diff --git a/lib/gui/app/models/flash-state.js b/lib/gui/app/models/flash-state.js
index 9c28ce1e..493d95dc 100644
--- a/lib/gui/app/models/flash-state.js
+++ b/lib/gui/app/models/flash-state.js
@@ -119,7 +119,8 @@ exports.setProgressState = (state) => {
   const data = _.assign({}, state, {
     percentage: _.isFinite(state.percentage)
       ? Math.floor(state.percentage)
-      : state.percentage,
+      // eslint-disable-next-line no-undefined
+      : undefined,
 
     speed: _.attempt(() => {
       if (_.isFinite(state.speed)) {
diff --git a/tests/gui/models/flash-state.spec.js b/tests/gui/models/flash-state.spec.js
index db35c667..d8229d6e 100644
--- a/tests/gui/models/flash-state.spec.js
+++ b/tests/gui/models/flash-state.spec.js
@@ -126,23 +126,6 @@ describe('Model: flashState', function () {
         }).to.not.throw('Missing flash fields: percentage')
       })
 
-      it('should throw if percentage is not a number', function () {
-        flashState.setFlashingFlag()
-        m.chai.expect(function () {
-          flashState.setProgressState({
-            flashing: 2,
-            verifying: 0,
-            successful: 0,
-            failed: 0,
-            type: 'write',
-            percentage: '50',
-            eta: 15,
-            speed: 100000000000,
-            totalSpeed: 200000000000
-          })
-        }).to.throw('Invalid state percentage: 50')
-      })
-
       it('should throw if percentage is outside maximum bound', function () {
         flashState.setFlashingFlag()
         m.chai.expect(function () {