diff --git a/src/controller/stream-controller.ts b/src/controller/stream-controller.ts
index d2f5bc2a700..a1d1581a6fe 100644
--- a/src/controller/stream-controller.ts
+++ b/src/controller/stream-controller.ts
@@ -681,7 +681,8 @@ export default class StreamController
 
     if (!this.startFragRequested) {
       this.setStartPosition(newDetails, sliding);
-    } else if (newDetails.live) {
+    } else if (newDetails.live && newDetails.PTSKnown) {
+      // Ensure Fragments have correct starts
       this.synchronizeToLiveEdge(newDetails);
     }