diff --git a/dom/media/MediaStreamGraph.cpp b/dom/media/MediaStreamGraph.cpp
index 8684de3a5b13..49e78f643e5b 100644
--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -1348,14 +1348,16 @@ MediaStreamGraphImpl::UpdateGraph(GraphTime aEndBlockingDecisions)
     stream->mStartBlocking = mStateComputedTime;
   }
 
-  // The loop is woken up so soon that IterationEnd() barely advances and we
-  // end up having aEndBlockingDecision == mStateComputedTime.
-  // Since stream blocking is computed in the interval of
-  // [mStateComputedTime, aEndBlockingDecision), it won't be computed at all.
-  // We should ensure next iteration so that pending blocking changes will be
-  // computed in next loop.
+  // If the loop is woken up so soon that IterationEnd() barely advances or
+  // if an offline graph is not currently rendering, we end up having
+  // aEndBlockingDecisions == mStateComputedTime.
+  // Since the process interval [mStateComputedTime, aEndBlockingDecision) is
+  // empty, Process() will not find any unblocked stream and so will not
+  // ensure another iteration.  If the graph should be rendering, then ensure
+  // another iteration to render.
   if (ensureNextIteration ||
-      aEndBlockingDecisions == mStateComputedTime) {
+      (aEndBlockingDecisions == mStateComputedTime &&
+       mStateComputedTime < mEndTime)) {
     EnsureNextIteration();
   }
 }