diff --git a/contentScript.js b/contentScript.js
index ee1dbfa..14fc67f 100644
--- a/contentScript.js
+++ b/contentScript.js
@@ -373,6 +373,10 @@ if (typeof Overlay === "undefined") {
     }
 
     calorieDiff() {
+      if (this.workoutStatus == null) {
+        return 0;
+      }
+
       const {minutes, seconds, calories} = this.workoutStatus;
 
       const expected = this.expectedCalories(minutes, seconds);