diff --git a/src/WaveTrack.cpp b/src/WaveTrack.cpp
index 075ddaf79..563bddb3d 100644
--- a/src/WaveTrack.cpp
+++ b/src/WaveTrack.cpp
@@ -254,8 +254,7 @@ bool WaveTrack::IsEmpty(double t0, double t1)
    {
       WaveClip *clip = it->GetData();
 
-      if (clip->GetStartTime() < t1-(1.0/mRate) &&
-          clip->GetEndTime()-(1.0/mRate) > t0) {
+      if (!clip->BeforeClip(t1) && !clip->AfterClip(t0)) {
          //printf("Overlapping clip: %.6f...%.6f\n",
          //       clip->GetStartTime(),
          //       clip->GetEndTime());
diff --git a/src/effects/Generator.cpp b/src/effects/Generator.cpp
index ba3d7eaf2..fc10b6994 100644
--- a/src/effects/Generator.cpp
+++ b/src/effects/Generator.cpp
@@ -43,11 +43,13 @@ bool Generator::Process()
          bool editClipCanMove;
          gPrefs->Read(wxT("/GUI/EditClipCanMove"), &editClipCanMove, true);
 
-         //if we can't move clips, check if generation is done on an empty place with enough
-         //duration before actually generate anything.
-         if (!editClipCanMove && track->IsEmpty(mT0, mT0+1.0/track->GetRate()) &&
-            !track->IsEmpty(mT0, mT0+mDuration-1.0/track->GetRate())) {
-            wxMessageBox(
+         //if we can't move clips, and we're generating into an empty space,
+         //make sure there's room.
+         if (!editClipCanMove &&
+	     track->IsEmpty(mT0, mT1+1.0/track->GetRate()) &&
+             !track->IsEmpty(mT0, mT0+mDuration-(mT1-mT0)-1.0/track->GetRate()))
+	 {
+             wxMessageBox(
                _("There is not enough room available to generate the audio"),
                _("Error"), wxICON_STOP);   
             Failure();
@@ -67,7 +69,7 @@ bool Generator::Process()
             else {
                // Transfer the data from the temporary track to the actual one
                tmp->Flush();
-               SetTimeWarper(new StepTimeWarper(mT1, mDuration-mT1));
+               SetTimeWarper(new StepTimeWarper(mT0+mDuration, mDuration-(mT1-mT0)));
                bGoodResult = track->ClearAndPaste(mT0, mT1, tmp, true,
                      false, GetTimeWarper());
                delete tmp;