diff --git a/src/components/views/right_panel/RoomHeaderButtons.tsx b/src/components/views/right_panel/RoomHeaderButtons.tsx
index 79bc57515fd..0826548664c 100644
--- a/src/components/views/right_panel/RoomHeaderButtons.tsx
+++ b/src/components/views/right_panel/RoomHeaderButtons.tsx
@@ -301,7 +301,7 @@ export default class RoomHeaderButtons extends HeaderButtons<IProps> {
                 title={_t("Threads")}
                 onClick={this.onThreadsPanelClicked}
                 isHighlighted={this.isPhase(RoomHeaderButtons.THREAD_PHASES)}
-                isUnread={this.state.threadNotificationColor > 0}
+                isUnread={this.state.threadNotificationColor > NotificationColor.None}
             >
                 <UnreadIndicator color={this.state.threadNotificationColor} />
             </HeaderButton>,
diff --git a/test/components/views/right_panel/RoomHeaderButtons-test.tsx b/test/components/views/right_panel/RoomHeaderButtons-test.tsx
index 89f7f87b153..a7f932b22db 100644
--- a/test/components/views/right_panel/RoomHeaderButtons-test.tsx
+++ b/test/components/views/right_panel/RoomHeaderButtons-test.tsx
@@ -70,8 +70,10 @@ describe("RoomHeaderButtons-test.tsx", function () {
 
     it("thread notification does change the thread button", () => {
         const { container } = getComponent(room);
+        expect(getThreadButton(container)!.className.includes("mx_RightPanel_headerButton_unread")).toBeFalsy();
 
         room.setThreadUnreadNotificationCount("$123", NotificationCountType.Total, 1);
+        expect(getThreadButton(container)!.className.includes("mx_RightPanel_headerButton_unread")).toBeTruthy();
         expect(isIndicatorOfType(container, "gray")).toBe(true);
 
         room.setThreadUnreadNotificationCount("$123", NotificationCountType.Highlight, 1);