diff --git a/src/emucore/tia/frame-manager/FrameLayoutDetector.cxx b/src/emucore/tia/frame-manager/FrameLayoutDetector.cxx
index 1fe79f651..5ae3be83b 100644
--- a/src/emucore/tia/frame-manager/FrameLayoutDetector.cxx
+++ b/src/emucore/tia/frame-manager/FrameLayoutDetector.cxx
@@ -181,12 +181,14 @@ void FrameLayoutDetector::onNextLine()
       if (myCurrentFrameTotalLines > frameLines - 3 || myTotalFrames == 0)
         ++myLinesWaitingForVsyncToStart;
 
-      if (myLinesWaitingForVsyncToStart > Metrics::waitForVsync) setState(State::waitForVsyncEnd);
+      if (myLinesWaitingForVsyncToStart > Metrics::waitForVsync) 
+        setState(State::waitForVsyncEnd);
 
       break;
 
     case State::waitForVsyncEnd:
-      if (++myLinesWaitingForVsyncToStart > Metrics::waitForVsync) setState(State::waitForVsyncStart);
+      if (++myLinesWaitingForVsyncToStart > Metrics::waitForVsync) 
+        setState(State::waitForVsyncStart);
 
       break;
 
@@ -232,7 +234,10 @@ void FrameLayoutDetector::finalizeFrame()
 {
   notifyFrameComplete();
 
-  if (myTotalFrames <= Metrics::initialGarbageFrames) return;
+  if (myTotalFrames <= Metrics::initialGarbageFrames) 
+    return;
+  if (myCurrentFrameFinalLines > Metrics::frameLinesPAL + Metrics::waitForVsync) 
+    return;
 
   // Calculate how close a frame is to PAL and NTSC based on scanlines. An odd scanline count
   // results into a penalty of 0.5 for PAL. The result is between 0.0 (<=262 scanlines) and