diff --git a/src/effects/Amplify.cpp b/src/effects/Amplify.cpp
index 21b16e939..82437e11f 100644
--- a/src/effects/Amplify.cpp
+++ b/src/effects/Amplify.cpp
@@ -179,13 +179,10 @@ bool EffectAmplify::Init()
 
 void EffectAmplify::Preview(bool dryOnly)
 {
-   double ratio = mRatio;
-   double peak = mPeak;
+   auto cleanup1 = valueRestorer( mRatio );
+   auto cleanup2 = valueRestorer( mPeak );
 
    Effect::Preview(dryOnly);
-
-   mRatio = ratio;
-   mPeak = peak;
 }
 
 void EffectAmplify::PopulateOrExchange(ShuttleGui & S)
diff --git a/src/effects/Equalization.cpp b/src/effects/Equalization.cpp
index 41338f0fa..954f733fb 100644
--- a/src/effects/Equalization.cpp
+++ b/src/effects/Equalization.cpp
@@ -1092,9 +1092,7 @@ bool EffectEqualization::ProcessOne(int count, WaveTrack * t,
          for(size_t j = mM - 1; j < wcopy; j++)
             buffer[i+j] = thisWindow[j];
 
-         float *tempP = thisWindow;
-         thisWindow = lastWindow;
-         lastWindow = tempP;
+         std::swap( thisWindow, lastWindow );
       }  //next i, lump of this block
 
       output->Append((samplePtr)buffer.get(), floatSample, block);
diff --git a/src/effects/Equalization48x.cpp b/src/effects/Equalization48x.cpp
index 594f76355..0a6c2170c 100644
--- a/src/effects/Equalization48x.cpp
+++ b/src/effects/Equalization48x.cpp
@@ -16,6 +16,7 @@
 #include "../Audacity.h"
 #include "../Experimental.h"
 #ifdef EXPERIMENTAL_EQ_SSE_THREADED
+#include "../MemoryX.h"
 #include "../Project.h"
 #include "Equalization.h"
 #include "../WaveTrack.h"
@@ -296,6 +297,7 @@ bool EffectEqualization48x::Process(EffectEqualization* effectEqualization)
    if(sMathPath)  // !!! Filter MUST BE QUAD WORD ALIGNED !!!!
       mEffectEqualization->mM=(mEffectEqualization->mM&(~15))+1;
    AllocateBuffersWorkers(sMathPath&MATH_FUNCTION_THREADED);
+   auto cleanup = finally( [&] { FreeBuffersWorkers(); } );
    SelectedTrackListOfKindIterator iter(Track::Wave, mEffectEqualization->mOutputTracks.get());
    WaveTrack *track = (WaveTrack *) iter.First();
    int count = 0;
@@ -316,7 +318,6 @@ bool EffectEqualization48x::Process(EffectEqualization* effectEqualization)
       track = (WaveTrack *) iter.Next();
       count++;
    }
-   FreeBuffersWorkers();
 
    mEffectEqualization->ReplaceProcessedTracks(!bBreakLoop); 
    return !bBreakLoop;
@@ -331,6 +332,7 @@ bool EffectEqualization48x::TrackCompare()
    if(sMathPath)  // !!! Filter MUST BE QUAD WORD ALIGNED !!!!
       mEffectEqualization->mM=(mEffectEqualization->mM&(~15))+1;
    AllocateBuffersWorkers(sMathPath&MATH_FUNCTION_THREADED);
+   auto cleanup = finally( [&] { FreeBuffersWorkers(); } );
    // Reset map
    // PRL:  These two maps aren't really used
    std::vector<Track*> SecondIMap;
@@ -402,9 +404,8 @@ bool EffectEqualization48x::TrackCompare()
       track = (WaveTrack *) iter.Next();
       track2 = (WaveTrack *) iter2.Next();
    }
-   FreeBuffersWorkers();
-   mEffectEqualization->ReplaceProcessedTracks(!bBreakLoop); 
-   return bBreakLoop;
+   mEffectEqualization->ReplaceProcessedTracks(!bBreakLoop);
+   return bBreakLoop; // return !bBreakLoop ?
 }
 
 bool EffectEqualization48x::DeltaTrack(WaveTrack * t, WaveTrack * t2, sampleCount start, sampleCount len)
@@ -446,6 +447,7 @@ bool EffectEqualization48x::Benchmark(EffectEqualization* effectEqualization)
    if(sMathPath)  // !!! Filter MUST BE QUAD WORD ALIGNED !!!!
       mEffectEqualization->mM=(mEffectEqualization->mM&(~15))+1;
    AllocateBuffersWorkers(MATH_FUNCTION_THREADED);
+   auto cleanup = finally( [&] { FreeBuffersWorkers(); } );
    SelectedTrackListOfKindIterator
       iter(Track::Wave, mEffectEqualization->mOutputTracks.get());
    long times[] = { 0,0,0,0,0 };
@@ -494,7 +496,6 @@ bool EffectEqualization48x::Benchmark(EffectEqualization* effectEqualization)
          times[i]=timer.Time();
       }
    }
-   FreeBuffersWorkers();
    mBenching=false;
    bBreakLoop=false;
    mEffectEqualization->ReplaceProcessedTracks(bBreakLoop); 
@@ -507,7 +508,7 @@ bool EffectEqualization48x::Benchmark(EffectEqualization* effectEqualization)
 
    wxMessageBox(wxString::Format(_("Benchmark times:\nOriginal: %s\nDefault Segmented: %s\nDefault Threaded: %s\nSSE: %s\nSSE Threaded: %s\n"),tsDefault.Format(wxT("%M:%S.%l")).c_str(), 
       tsDefaultEnhanced.Format(wxT("%M:%S.%l")).c_str(), tsDefaultThreaded.Format(wxT("%M:%S.%l")).c_str(),tsSSE.Format(wxT("%M:%S.%l")).c_str(),tsSSEThreaded.Format(wxT("%M:%S.%l")).c_str()));
-   return bBreakLoop;
+   return bBreakLoop; // return !bBreakLoop ?
 }
 
 bool EffectEqualization48x::ProcessTail(WaveTrack * t, WaveTrack * output, sampleCount start, sampleCount len)
@@ -862,30 +863,32 @@ bool EffectEqualization48x::ProcessOne4x(int count, WaveTrack * t,
       ProcessTail(t, output.get(), start, len);
    return bBreakLoop;
 }
+
 void *EQWorker::Entry()
 {
    while(!mExitLoop) {
-      mMutex->Lock();
-      bool bufferAquired=false;
-      for(int i=0;i<mBufferInfoCount;i++)
-         if(mBufferInfoList[i].mBufferStatus==BufferReady) { // we found an unlocked ready buffer
-            bufferAquired=true;
-            mBufferInfoList[i].mBufferStatus=BufferBusy; // we own it now
-            mMutex->Unlock();
-            switch (mProcessingType)
-            {
+      int i = 0;
+      {
+         wxMutexLocker locker( mMutex );
+         for(; i < mBufferInfoCount; i++) {
+            if(mBufferInfoList[i].mBufferStatus==BufferReady) { // we found an unlocked ready buffer
+               mBufferInfoList[i].mBufferStatus=BufferBusy; // we own it now
+               break;
+            }
+         }
+      }
+      if ( i < mBufferInfoCount ) {
+         switch (mProcessingType)
+         {
             case 1:
                mEffectEqualization48x->ProcessBuffer1x(&mBufferInfoList[i]);
                break;
-            case 4: 
+            case 4:
                mEffectEqualization48x->ProcessBuffer4x(&mBufferInfoList[i]);
                break;
-            }
-            mBufferInfoList[i].mBufferStatus=BufferDone; // we're done
-            break;
-         } 
-         if(!bufferAquired)
-            mMutex->Unlock();
+         }
+         mBufferInfoList[i].mBufferStatus=BufferDone; // we're done
+      }
    }
    return NULL;
 }
@@ -940,7 +943,7 @@ bool EffectEqualization48x::ProcessOne1x4xThreaded(int count, WaveTrack * t,
       bBreakLoop=mEffectEqualization->TrackProgress(count, (double)(bigBlocksWritten)/bigRuns.as_double());
       if( bBreakLoop )
          break;
-      mDataMutex.Lock(); // Get in line for data
+      wxMutexLocker locker( mDataMutex ); // Get in line for data
       // process as many blocks as we can
       while((mBufferInfo[currentIndex].mBufferStatus==BufferDone) && (bigBlocksWritten<bigRuns)) { // data is ours
          output->Append((samplePtr)&mBufferInfo[currentIndex].mBufferDest[0][(bigBlocksWritten?mBlockSize:0)+(mFilterSize>>1)], floatSample, subBufferSize-((bigBlocksWritten?mBlockSize:0)+(mFilterSize>>1)));
@@ -961,7 +964,6 @@ bool EffectEqualization48x::ProcessOne1x4xThreaded(int count, WaveTrack * t,
          } else mBufferInfo[currentIndex].mBufferStatus=BufferEmpty; // this is completely unecessary
          currentIndex=(currentIndex+1)%mWorkerDataCount;
       } 
-      mDataMutex.Unlock(); // Get back in line for data
    }
    if(singleProcessLength && !bBreakLoop) {
       t->Get((samplePtr)mBigBuffer.get(), floatSample, currentSample, singleProcessLength+mBlockSize+(mFilterSize>>1));
@@ -1237,7 +1239,7 @@ bool EffectEqualization48x::ProcessOne8xThreaded(int count, WaveTrack * t,
       {
          break;
       }
-      mDataMutex.Lock(); // Get in line for data
+      wxMutexLocker locker( mDataMutex ); // Get in line for data
       // process as many blocks as we can
       while((mBufferInfo[currentIndex].mBufferStatus==BufferDone) && (bigBlocksWritten<bigRuns)) { // data is ours
          output->Append((samplePtr)&mBufferInfo[currentIndex].mBufferDest[0][(bigBlocksWritten?mBlockSize:0)+(mFilterSize>>1)], floatSample, mSubBufferSize-((bigBlocksWritten?mBlockSize:0)+(mFilterSize>>1)));
@@ -1258,7 +1260,6 @@ bool EffectEqualization48x::ProcessOne8xThreaded(int count, WaveTrack * t,
          } else mBufferInfo[currentIndex].mBufferStatus=BufferEmpty; // this is completely unecessary
          currentIndex=(currentIndex+1)%mWorkerDataCount;
       } 
-      mDataMutex.Unlock(); // Get back in line for data
    }
    if(singleProcessLength && !bBreakLoop) {
       t->Get((samplePtr)mBigBuffer.get(), floatSample, currentSample, singleProcessLength+mBlockSize+(mFilterSize>>1));
diff --git a/src/effects/NoiseReduction.cpp b/src/effects/NoiseReduction.cpp
index 24e494151..647879780 100644
--- a/src/effects/NoiseReduction.cpp
+++ b/src/effects/NoiseReduction.cpp
@@ -1656,14 +1656,11 @@ void EffectNoiseReduction::Dialog::OnPreview(wxCommandEvent & WXUNUSED(event))
       return;
 
    // Save & restore parameters around Preview, because we didn't do OK.
-   EffectNoiseReduction::Settings oldSettings(*m_pSettings);
-
+   auto cleanup = valueRestorer( *m_pSettings );
    *m_pSettings = mTempSettings;
    m_pSettings->mDoProfile = false;
 
    m_pEffect->Preview();
-
-   *m_pSettings = oldSettings;
 }
 
 void EffectNoiseReduction::Dialog::OnReduceNoise( wxCommandEvent & WXUNUSED(event))
diff --git a/src/effects/NoiseRemoval.cpp b/src/effects/NoiseRemoval.cpp
index 26b50e2c6..761bf6098 100644
--- a/src/effects/NoiseRemoval.cpp
+++ b/src/effects/NoiseRemoval.cpp
@@ -224,7 +224,6 @@ bool EffectNoiseRemoval::Process()
          auto len = end - start;
 
          if (!ProcessOne(count, track, start, len)) {
-            Cleanup();
             bGoodResult = false;
             break;
          }
@@ -238,8 +237,6 @@ bool EffectNoiseRemoval::Process()
       mDoProfile = false;
    }
 
-   if (bGoodResult)
-      Cleanup();
    this->ReplaceProcessedTracks(bGoodResult);
    return bGoodResult;
 }
@@ -305,7 +302,7 @@ void EffectNoiseRemoval::Initialize()
    }
 }
 
-void EffectNoiseRemoval::Cleanup()
+void EffectNoiseRemoval::End()
 {
    hFFT.reset();
 
@@ -322,6 +319,8 @@ void EffectNoiseRemoval::Cleanup()
    mInWaveBuffer.reset();
    mWindow.reset();
    mOutOverlapBuffer.reset();
+
+   mOutputTrack.reset();
 }
 
 void EffectNoiseRemoval::StartNewTrack()
@@ -579,9 +578,6 @@ bool EffectNoiseRemoval::ProcessOne(int count, WaveTrack * track,
          bool bResult = track->ClearAndPaste(t0, t0 + tLen, mOutputTrack.get(), true, false);
          wxASSERT(bResult); // TO DO: Actually handle this.
       }
-
-      // Delete the outputTrack now that its data is inserted in place
-      mOutputTrack.reset();
    }
 
    return bLoopSuccess;
@@ -688,14 +684,16 @@ void NoiseRemovalDialog::OnPreview(wxCommandEvent & WXUNUSED(event))
    m_pEffect->mFreqSmoothingHz =  mFreq;
    m_pEffect->mAttackDecayTime =  mTime;
 
-   m_pEffect->Preview();
+   auto cleanup = finally( [&] {
+      m_pEffect->mSensitivity = oldSensitivity;
+      m_pEffect->mNoiseGain = oldGain;
+      m_pEffect->mFreqSmoothingHz =  oldFreq;
+      m_pEffect->mAttackDecayTime =  oldTime;
+      m_pEffect->mbLeaveNoise = oldLeaveNoise;
+      m_pEffect->mDoProfile = oldDoProfile;
+   } );
 
-   m_pEffect->mSensitivity = oldSensitivity;
-   m_pEffect->mNoiseGain = oldGain;
-   m_pEffect->mFreqSmoothingHz =  oldFreq;
-   m_pEffect->mAttackDecayTime =  oldTime;
-   m_pEffect->mbLeaveNoise = oldLeaveNoise;
-   m_pEffect->mDoProfile = oldDoProfile;
+   m_pEffect->Preview();
 }
 
 void NoiseRemovalDialog::OnRemoveNoise( wxCommandEvent & WXUNUSED(event))
diff --git a/src/effects/NoiseRemoval.h b/src/effects/NoiseRemoval.h
index ba13bb4dc..3e888aa2a 100644
--- a/src/effects/NoiseRemoval.h
+++ b/src/effects/NoiseRemoval.h
@@ -61,6 +61,7 @@ public:
    bool Init() override;
    bool CheckWhetherSkipEffect() override;
    bool Process() override;
+   void End() override;
 
 private:
 
@@ -98,7 +99,6 @@ private:
    void RemoveNoise();
    void RotateHistoryWindows();
    void FinishTrack();
-   void Cleanup();
 
    // Variables that only exist during processing
    std::unique_ptr<WaveTrack> mOutputTrack;
diff --git a/src/effects/SBSMSEffect.cpp b/src/effects/SBSMSEffect.cpp
index 91070f553..8278cd7ac 100644
--- a/src/effects/SBSMSEffect.cpp
+++ b/src/effects/SBSMSEffect.cpp
@@ -34,8 +34,6 @@ public:
    ResampleBuf()
    {
       processed = 0;
-      outputLeftTrack = NULL;
-      outputRightTrack = NULL;
    }
 
    ~ResampleBuf()
diff --git a/src/effects/SimpleMono.cpp b/src/effects/SimpleMono.cpp
index da48e3595..cd247ded7 100644
--- a/src/effects/SimpleMono.cpp
+++ b/src/effects/SimpleMono.cpp
@@ -103,10 +103,9 @@ bool EffectSimpleMono::ProcessOne(WaveTrack * track,
       track->Get((samplePtr) buffer.get(), floatSample, s, block);
 
       //Process the buffer.  If it fails, clean up and exit.
-      if (!ProcessSimpleMono(buffer.get(), block)) {
+      if (!ProcessSimpleMono(buffer.get(), block))
          //Return false because the effect failed.
          return false;
-      }
 
       //Processing succeeded. copy the newly-changed samples back
       //onto the track.
@@ -118,9 +117,8 @@ bool EffectSimpleMono::ProcessOne(WaveTrack * track,
       //Update the Progress meter
       if (TrackProgress(mCurTrackNum,
                         (s - start).as_double() /
-                        len)) {
+                        len))
          return false;
-      }
    }
 
    //Return true because the effect processing succeeded.
diff --git a/src/effects/SoundTouchEffect.cpp b/src/effects/SoundTouchEffect.cpp
index 1783d16c5..b56de741c 100644
--- a/src/effects/SoundTouchEffect.cpp
+++ b/src/effects/SoundTouchEffect.cpp
@@ -159,14 +159,17 @@ bool EffectSoundTouch::ProcessWithTimeWarper(const TimeWarper &warper)
    if (bGoodResult)
       ReplaceProcessedTracks(bGoodResult);
 
-   mSoundTouch.reset();
-
 //   mT0 = mCurT0;
 //   mT1 = mCurT0 + m_maxNewLength; // Update selection.
 
    return bGoodResult;
 }
 
+void EffectSoundTouch::End()
+{
+   mSoundTouch.reset();
+}
+
 //ProcessOne() takes a track, transforms it to bunch of buffer-blocks,
 //and executes ProcessSoundTouch on these blocks
 bool EffectSoundTouch::ProcessOne(WaveTrack *track,
@@ -345,7 +348,7 @@ bool EffectSoundTouch::ProcessStereo(
    return true;
 }
 
-bool EffectSoundTouch::ProcessStereoResults(const unsigned int outputCount,
+bool EffectSoundTouch::ProcessStereoResults(const size_t outputCount,
                                             WaveTrack* outputLeftTrack,
                                             WaveTrack* outputRightTrack)
 {
diff --git a/src/effects/SoundTouchEffect.h b/src/effects/SoundTouchEffect.h
index ed38f94ad..7588766cf 100644
--- a/src/effects/SoundTouchEffect.h
+++ b/src/effects/SoundTouchEffect.h
@@ -39,6 +39,10 @@ class EffectSoundTouch /* not final */ : public Effect
 {
 public:
 
+   // Effect implementation
+
+   void End() override;
+
    // EffectSoundTouch implementation
 
 #ifdef USE_MIDI
@@ -66,7 +70,7 @@ private:
    bool ProcessStereo(WaveTrack* leftTrack, WaveTrack* rightTrack,
                      sampleCount start, sampleCount end,
                       const TimeWarper &warper);
-   bool ProcessStereoResults(const unsigned int outputCount,
+   bool ProcessStereoResults(const size_t outputCount,
                               WaveTrack* outputLeftTrack,
                               WaveTrack* outputRightTrack);
 
diff --git a/src/effects/StereoToMono.cpp b/src/effects/StereoToMono.cpp
index a5e257497..f4721f067 100644
--- a/src/effects/StereoToMono.cpp
+++ b/src/effects/StereoToMono.cpp
@@ -125,11 +125,15 @@ bool EffectStereoToMono::Process()
       count++;
    }
 
-   mOutTrack.reset();
    this->ReplaceProcessedTracks(bGoodResult);
    return bGoodResult;
 }
 
+void EffectStereoToMono::End()
+{
+   mOutTrack.reset();
+}
+
 bool EffectStereoToMono::ProcessOne(int count)
 {
    float  curLeftFrame;
diff --git a/src/effects/StereoToMono.h b/src/effects/StereoToMono.h
index d65f4eff6..754a7ba19 100644
--- a/src/effects/StereoToMono.h
+++ b/src/effects/StereoToMono.h
@@ -41,6 +41,7 @@ public:
    // Effect implementation
 
    bool Process() override;
+   void End() override;
    bool IsHidden() override;
 
 private:
diff --git a/src/effects/TimeScale.cpp b/src/effects/TimeScale.cpp
index 225493174..1501726ce 100644
--- a/src/effects/TimeScale.cpp
+++ b/src/effects/TimeScale.cpp
@@ -165,9 +165,8 @@ double EffectTimeScale::CalcPreviewInputLength(double previewLength)
 void EffectTimeScale::Preview(bool dryOnly)
 {
    previewSelectedDuration = Effect::GetDuration();
-   bPreview = true;
+   auto cleanup = valueRestorer( bPreview, true );
    Effect::Preview(dryOnly);
-   bPreview = false;
 }
 
 bool EffectTimeScale::Process()
diff --git a/src/effects/nyquist/Nyquist.cpp b/src/effects/nyquist/Nyquist.cpp
index a402dc8dc..6d4736bb8 100644
--- a/src/effects/nyquist/Nyquist.cpp
+++ b/src/effects/nyquist/Nyquist.cpp
@@ -117,6 +117,8 @@ END_EVENT_TABLE()
 
 NyquistEffect::NyquistEffect(const wxString &fName)
 {
+   mOutputTrack[0] = mOutputTrack[1] = nullptr;
+
    mAction = _("Applying Nyquist Effect...");
    mInputCmd = wxEmptyString;
    mCmd = wxEmptyString;
@@ -670,6 +672,13 @@ _("Selection too long for Nyquist code.\nMaximum allowed selection is %ld sample
          nyx_set_os_callback(StaticOSCallback, (void *)this);
          nyx_capture_output(StaticOutputCallback, (void *)this);
 
+         auto cleanup = finally( [&] {
+            nyx_capture_output(NULL, (void *)NULL);
+            nyx_set_os_callback(NULL, (void *)NULL);
+            nyx_cleanup();
+         } );
+
+
          if (mVersion >= 4)
          {
             mPerTrackProps = wxEmptyString;
@@ -709,10 +718,6 @@ _("Selection too long for Nyquist code.\nMaximum allowed selection is %ld sample
 
          success = ProcessOne();
 
-         nyx_capture_output(NULL, (void *)NULL);
-         nyx_set_os_callback(NULL, (void *)NULL);
-         nyx_cleanup();
-
          // Reset previous locale
          wxSetlocale(LC_NUMERIC, prevlocale);
 
@@ -1110,16 +1115,23 @@ bool NyquistEffect::ProcessOne()
       cmd += mCmd;
    }
 
-   int i;
-   for (i = 0; i < mCurNumChannels; i++) {
+   // Put the fetch buffers in a clean initial state
+   for (size_t i = 0; i < mCurNumChannels; i++)
       mCurBuffer[i].Free();
-   }
 
+   // Guarantee release of memory when done
+   auto cleanup = finally( [&] {
+      for (size_t i = 0; i < mCurNumChannels; i++)
+         mCurBuffer[i].Free();
+   } );
+
+   // Evaluate the expression, which may invoke the get callback, but often does
+   // not, leaving that to delayed evaluation of the output sound
    rval = nyx_eval_expression(cmd.mb_str(wxConvUTF8));
 
    // Audacity has no idea how long Nyquist processing will take, but
    // can monitor audio being returned.
-   // Anything other than audio should be returmed almost instantly
+   // Anything other than audio should be returned almost instantly
    // so notify the user that process has completed (bug 558)
    if ((rval != nyx_audio) && ((mCount + mCurNumChannels) == mNumSelectedChannels)) {
       if (mCurNumChannels == 1) {
@@ -1225,19 +1237,30 @@ bool NyquistEffect::ProcessOne()
       return false;
    }
 
+   std::unique_ptr<WaveTrack> outputTrack[2];
+
    double rate = mCurTrack[0]->GetRate();
-   for (i = 0; i < outChannels; i++) {
+   for (size_t i = 0; i < outChannels; i++) {
       sampleFormat format = mCurTrack[i]->GetSampleFormat();
 
       if (outChannels == (int)mCurNumChannels) {
          rate = mCurTrack[i]->GetRate();
       }
 
-      mOutputTrack[i] = mFactory->NewWaveTrack(format, rate);
+      outputTrack[i] = mFactory->NewWaveTrack(format, rate);
+
+      // Clean the initial buffer states again for the get callbacks
+      // -- is this really needed?
       mCurBuffer[i].Free();
    }
 
-   int success = nyx_get_audio(StaticPutCallback, (void *)this);
+   // Now fully evaluate the sound
+   int success;
+   {
+      auto vr0 = valueRestorer( mOutputTrack[0], outputTrack[0].get() );
+      auto vr1 = valueRestorer( mOutputTrack[1], outputTrack[1].get() );
+      success = nyx_get_audio(StaticPutCallback, (void *)this);
+   }
 
    // See if GetCallback found read errors
    if (mFailedFileName.IsOk())
@@ -1250,38 +1273,29 @@ bool NyquistEffect::ProcessOne()
       // what, then?
       success = false;
 
-   if (!success) {
-      for(i = 0; i < outChannels; i++) {
-         mOutputTrack[i].reset();
-      }
-
+   if (!success)
       return false;
-   }
 
-   for (i = 0; i < outChannels; i++) {
-      mOutputTrack[i]->Flush();
-      mCurBuffer[i].Free();
-      mOutputTime = mOutputTrack[i]->GetEndTime();
+   for (size_t i = 0; i < outChannels; i++) {
+      outputTrack[i]->Flush();
+      mOutputTime = outputTrack[i]->GetEndTime();
 
       if (mOutputTime <= 0) {
          wxMessageBox(_("Nyquist did not return audio.\n"),
                       wxT("Nyquist"),
                       wxOK | wxCENTRE, mUIParent);
-         for (int j = 0; j < outChannels; j++) {
-            mOutputTrack[j].reset();
-         }
          return true;
       }
    }
 
-   for (i = 0; i < mCurNumChannels; i++) {
+   for (size_t i = 0; i < mCurNumChannels; i++) {
       WaveTrack *out;
 
       if (outChannels == (int)mCurNumChannels) {
-         out = mOutputTrack[i].get();
+         out = outputTrack[i].get();
       }
       else {
-         out = mOutputTrack[0].get();
+         out = outputTrack[0].get();
       }
 
       if (mMergeClips < 0) {
@@ -1310,9 +1324,6 @@ bool NyquistEffect::ProcessOne()
       mFirstInGroup = false;
    }
 
-   for (i = 0; i < outChannels; i++) {
-      mOutputTrack[i].reset();
-   }
    mProjectChanged = true;
    return true;
 }
diff --git a/src/effects/nyquist/Nyquist.h b/src/effects/nyquist/Nyquist.h
index 7009d4ece..6db9e0b04 100644
--- a/src/effects/nyquist/Nyquist.h
+++ b/src/effects/nyquist/Nyquist.h
@@ -224,7 +224,7 @@ private:
    sampleCount       mCurBufferStart[2];
    size_t            mCurBufferLen[2];
 
-   std::unique_ptr<WaveTrack> mOutputTrack[2];
+   WaveTrack        *mOutputTrack[2];
 
    wxArrayString     mCategories;