diff --git a/src/Envelope.cpp b/src/Envelope.cpp
index 1fb1b7da2..e483bb2b4 100644
--- a/src/Envelope.cpp
+++ b/src/Envelope.cpp
@@ -198,7 +198,7 @@ EnvPoint *Envelope::AddPointAtEnd( double t, double val )
 
 void Envelope::CopyFrom(const Envelope *e, double t0, double t1)
 {
-   wxASSERT( t0 < t1 );
+   wxASSERT( t0 <= t1 );
 
    mOffset   = wxMax(t0, e->mOffset);
    mTrackLen = wxMin(t1, e->mOffset + e->mTrackLen) - mOffset;
diff --git a/src/Sequence.cpp b/src/Sequence.cpp
index 955672150..726029298 100644
--- a/src/Sequence.cpp
+++ b/src/Sequence.cpp
@@ -378,8 +378,10 @@ float Sequence::GetRMS(sampleCount start, sampleCount len, bool mayThrow) const
 
 std::unique_ptr<Sequence> Sequence::Copy(sampleCount s0, sampleCount s1) const
 {
-   if (s0 >= s1 || s0 >= mNumSamples || s1 < 0)
-      return {};
+   auto dest = std::make_unique<Sequence>(mDirManager, mSampleFormat);
+   if (s0 >= s1 || s0 >= mNumSamples || s1 < 0) {
+      return dest;
+   }
 
    int numBlocks = mBlock.size();
 
@@ -391,7 +393,6 @@ std::unique_ptr<Sequence> Sequence::Copy(sampleCount s0, sampleCount s1) const
    wxUnusedVar(numBlocks);
    wxASSERT(b0 <= b1);
 
-   auto dest = std::make_unique<Sequence>(mDirManager, mSampleFormat);
    dest->mBlock.reserve(b1 - b0 + 1);
 
    SampleBuffer buffer(mMaxSamples, mSampleFormat);