diff --git a/packages/upload/src/vaadin-upload-file-mixin.js b/packages/upload/src/vaadin-upload-file-mixin.js
index 3fa8c7a1e4..763d13970c 100644
--- a/packages/upload/src/vaadin-upload-file-mixin.js
+++ b/packages/upload/src/vaadin-upload-file-mixin.js
@@ -161,12 +161,16 @@ export const UploadFileMixin = (superClass) =>
      * @protected
      */
     _shouldSetFocus(event) {
-      return !this.disabled && event.composedPath()[0] === this;
+      return event.composedPath()[0] === this;
     }
 
     /** @private */
     __disabledChanged(disabled) {
-      this.tabIndex = disabled ? -1 : 0;
+      if (disabled) {
+        this.removeAttribute('tabindex');
+      } else {
+        this.setAttribute('tabindex', this.tabindex);
+      }
     }
 
     /** @private */
diff --git a/packages/upload/test/file.common.js b/packages/upload/test/file.common.js
index 3765993da4..d287436e25 100644
--- a/packages/upload/test/file.common.js
+++ b/packages/upload/test/file.common.js
@@ -82,12 +82,15 @@ describe('<vaadin-upload-file> element', () => {
     it('should be focusable by default', () => {
       fileElement.focus();
       expect(fileElement.hasAttribute('focused')).to.be.true;
+      expect(document.activeElement).to.equal(fileElement);
     });
 
-    it('should not be focusable when disabled', () => {
+    it('should not be focusable when disabled', async () => {
       fileElement.disabled = true;
+      await nextUpdate(fileElement);
       fileElement.focus();
       expect(fileElement.hasAttribute('focused')).to.be.false;
+      expect(document.activeElement).to.not.equal(fileElement);
     });
 
     it('should not add focus-ring to the host on programmatic focus', () => {