diff --git a/services/surfaceflinger/Scheduler/VSyncReactor.cpp b/services/surfaceflinger/Scheduler/VSyncReactor.cpp
index 186a2d6..9b8f310 100644
--- a/services/surfaceflinger/Scheduler/VSyncReactor.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncReactor.cpp
@@ -217,6 +217,11 @@
         mMoreSamplesNeeded = mTracker.needsMoreSamples();
     }
 
+    if (mExternalIgnoreFences) {
+      // keep HWVSync on as long as we ignore present fences.
+      mMoreSamplesNeeded = true;
+    }
+
     if (!mMoreSamplesNeeded) {
         setIgnorePresentFencesInternal(false);
     }