diff --git a/src/AdjustSync.cpp b/src/AdjustSync.cpp
index 0234cffbf4..7258f0dcbb 100644
--- a/src/AdjustSync.cpp
+++ b/src/AdjustSync.cpp
@@ -329,6 +329,12 @@ void AdjustSync::GetSyncChangeTextSong( vector<RString> &vsAddTo )
 {
 	if( GAMESTATE->m_pCurSong.Get() )
 	{
+#define SEGMENTS_MISMATCH_MESSAGE(orig, test, segments_name) \
+	if(orig.size() != test.size()) \
+	{ \
+		LuaHelpers::ReportScriptError("The sync overlay's " #segments_name " segment list is a different size from the song's.  Please report this bug with steps to reproduce it."); \
+	}
+
 		unsigned int iOriginalSize = vsAddTo.size();
 		TimingData &original = s_vpTimingDataOriginal[0];
 		TimingData &testing = GAMESTATE->m_pCurSong->m_SongTiming;
@@ -350,7 +356,8 @@ void AdjustSync::GetSyncChangeTextSong( vector<RString> &vsAddTo )
 
 		const vector<TimingSegment *> &bpmTest = testing.GetTimingSegments(SEGMENT_BPM);
 		const vector<TimingSegment *> &bpmOrig = original.GetTimingSegments(SEGMENT_BPM);
-		for( unsigned i=0; i< bpmTest.size(); i++ )
+		SEGMENTS_MISMATCH_MESSAGE(bpmOrig, bpmTest, bpm);
+		for(size_t i= 0; i < bpmTest.size() && i < bpmOrig.size(); i++)
 		{
 			float fNew = Quantize( ToBPM(bpmTest[i])->GetBPM(), 0.001f );
 			float fOld = Quantize( ToBPM(bpmOrig[i])->GetBPM(), 0.001f );
@@ -373,7 +380,8 @@ void AdjustSync::GetSyncChangeTextSong( vector<RString> &vsAddTo )
 		const vector<TimingSegment *> &stopTest = testing.GetTimingSegments(SEGMENT_STOP);
 		const vector<TimingSegment *> &stopOrig = original.GetTimingSegments(SEGMENT_STOP);
 
-		for( unsigned i=0; i< stopTest.size(); i++ )
+		SEGMENTS_MISMATCH_MESSAGE(stopOrig, stopTest, stop);
+		for(size_t i= 0; i < stopTest.size() && i < stopOrig.size(); i++)
 		{
 			float fOld = Quantize( ToStop(stopOrig[i])->GetPause(), 0.001f );
 			float fNew = Quantize( ToStop(stopTest[i])->GetPause(), 0.001f );
@@ -395,7 +403,8 @@ void AdjustSync::GetSyncChangeTextSong( vector<RString> &vsAddTo )
 		const vector<TimingSegment *> &delyTest = testing.GetTimingSegments(SEGMENT_DELAY);
 		const vector<TimingSegment *> &delyOrig = original.GetTimingSegments(SEGMENT_DELAY);
 
-		for( unsigned i=0; i< delyTest.size(); i++ )
+		SEGMENTS_MISMATCH_MESSAGE(delyOrig, delyTest, delay);
+		for(size_t i= 0; i < delyTest.size() && i < delyOrig.size(); i++)
 		{
 			if( delyTest[i] == delyOrig[i] )
 				continue;
@@ -426,6 +435,7 @@ void AdjustSync::GetSyncChangeTextSong( vector<RString> &vsAddTo )
 		{
 			vsAddTo.push_back( ssprintf(TAPS_IGNORED.GetValue(), s_iStepsFiltered) );
 		}
+#undef SEGMENTS_MISMATCH_MESSAGE
 	}
 }
 
diff --git a/src/TimingData.cpp b/src/TimingData.cpp
index 9ffc1de876..fd2311f453 100644
--- a/src/TimingData.cpp
+++ b/src/TimingData.cpp
@@ -384,16 +384,58 @@ void TimingData::AddSegment( const TimingSegment *seg )
 			// get the segment before last; if we're on the same
 			// row, get the segment in effect before 'cur'
 			if( bOnSameRow && index > 0 )
-				prev = vSegs[index - 1];
-
-			// if true, this is redundant segment change
-			if( (*prev) == (*seg) )
 			{
-				if( prev != cur )
-					EraseSegment( vSegs, index, cur );
-				return;
+				prev = vSegs[index - 1];
 			}
 
+			// If there is another segment after this one, it might become
+			// redundant when this one is inserted.
+			// If the next segment is redundant, we want to move its starting row
+			// to the row the new segment is being added at instead of erasing it
+			// and adding the new segment.
+			// If the new segment is also redundant, erase the next segment because
+			// that effectively moves it back to the prev segment. -Kyz
+			if(static_cast<size_t>(index) < vSegs.size() - 1)
+			{
+				TimingSegment* next= vSegs[index + 1];
+				if((*seg) == (*next))
+				{
+					// The segment after this new one is redundant.
+					if((*seg) == (*prev))
+					{
+						// This new segment is redundant.  Erase the next segment and
+						// ignore this new one.
+						EraseSegment(vSegs, index + 1, next);
+						if( prev != cur )
+						{
+							EraseSegment( vSegs, index, cur );
+						}
+						return;
+					}
+					else
+					{
+						// Move the next segment's start back to this row.
+						next->SetRow(seg->GetRow());
+						if( prev != cur )
+						{
+							EraseSegment( vSegs, index, cur );
+						}
+						return;
+					}
+				}
+			}
+			else
+			{
+				// if true, this is redundant segment change
+				if( (*prev) == (*seg) )
+				{
+					if( prev != cur )
+					{
+						EraseSegment( vSegs, index, cur );
+					}
+					return;
+				}
+			}
 			break;
 		}
 	}