diff --git a/Source/FamiTrackerDoc.cpp b/Source/FamiTrackerDoc.cpp
index e81d8caa..43303d9f 100644
--- a/Source/FamiTrackerDoc.cpp
+++ b/Source/FamiTrackerDoc.cpp
@@ -2571,6 +2571,11 @@ const CSongData &CFamiTrackerDoc::GetSongData(unsigned int Index) const		// // /
 	return *m_pTracks[Index];
 }
 
+std::unique_ptr<CSongData> CFamiTrackerDoc::ReplaceSong(unsigned Index, std::unique_ptr<CSongData> pSong) {		// // //
+	m_pTracks[Index].swap(pSong);
+	return std::move(pSong);
+}
+
 unsigned int CFamiTrackerDoc::GetTrackCount() const
 {
 	return m_pTracks.size();
@@ -3277,30 +3282,6 @@ bool CFamiTrackerDoc::ArePatternsSame(unsigned int Track, unsigned int Channel,
 	return song.GetPattern(Channel, Pattern1) == song.GetPattern(Channel, Pattern2);
 }
 
-void CFamiTrackerDoc::PopulateUniquePatterns(unsigned int Track)		// // //
-{
-	const int Rows = GetPatternLength(Track);
-	const int Frames = GetFrameCount(Track);
-	const auto &Song = GetSongData(Track);
-	auto pNew = std::make_unique<CSongData>(Rows);
-
-	pNew->SetSongSpeed(GetSongSpeed(Track));
-	pNew->SetSongTempo(GetSongTempo(Track));
-	pNew->SetFrameCount(Frames);
-	pNew->SetSongGroove(GetSongGroove(Track));
-	pNew->SetTitle(GetTrackTitle(Track));
-
-	for (int c = 0; c < GetChannelCount(); c++) {
-		pNew->SetEffectColumnCount(c, GetEffColumns(Track, c));
-		for (int f = 0; f < Frames; f++) {
-			pNew->SetFramePattern(f, c, f);
-			pNew->GetPattern(c, f) = Song.GetPattern(c, Song.GetFramePattern(f, c));
-		}
-	}
-
-	m_pTracks[Track] = std::move(pNew);
-}
-
 void CFamiTrackerDoc::SwapInstruments(int First, int Second)
 {
 	// Swap instruments
diff --git a/Source/FamiTrackerDoc.h b/Source/FamiTrackerDoc.h
index 0f8eba49..5551a116 100644
--- a/Source/FamiTrackerDoc.h
+++ b/Source/FamiTrackerDoc.h
@@ -147,6 +147,7 @@ class CFamiTrackerDoc : public CDocument, public CFTMComponentInterface
 	// Local (song) data
 	CSongData		&GetSongData(unsigned int Index);		// // //
 	const CSongData	&GetSongData(unsigned int Index) const;		// // //
+	std::unique_ptr<CSongData> ReplaceSong(unsigned Index, std::unique_ptr<CSongData> pSong);		// // // returns old song
 
 	void			SetPatternLength(unsigned int Track, unsigned int Length);
 	void			SetFrameCount(unsigned int Track, unsigned int Count);
@@ -184,8 +185,6 @@ class CFamiTrackerDoc : public CDocument, public CFTMComponentInterface
 	void			ClearPatterns(unsigned int Track);
 	void			ClearPattern(unsigned int Track, unsigned int Frame, unsigned int Channel);
 	
-	void			PopulateUniquePatterns(unsigned int Track);		// // //
-
 	bool			InsertRow(unsigned int Track, unsigned int Frame, unsigned int Channel, unsigned int Row);
 	bool			ClearRowField(unsigned int Track, unsigned int Frame, unsigned int Channel, unsigned int Row, cursor_column_t Column);
 	bool			RemoveNote(unsigned int Track, unsigned int Frame, unsigned int Channel, unsigned int Row);
diff --git a/Source/MainFrm.cpp b/Source/MainFrm.cpp
index 676046e0..7addf670 100644
--- a/Source/MainFrm.cpp
+++ b/Source/MainFrm.cpp
@@ -3571,16 +3571,7 @@ void CMainFrame::OnEditRemoveUnusedSamples()
 
 void CMainFrame::OnEditPopulateUniquePatterns()		// // //
 {
-	CFamiTrackerDoc *pDoc = static_cast<CFamiTrackerDoc*>(GetActiveDocument());
-
-	if (AfxMessageBox(IDS_POPULATE_PATTERNS, MB_YESNO | MB_ICONWARNING | MB_DEFBUTTON2) == IDNO)
-		return;
-	
-	pDoc->PopulateUniquePatterns(m_iTrack);
-	pDoc->SetModifiedFlag();
-	pDoc->SetExceededFlag();
-	ResetUndo();
-	pDoc->UpdateAllViews(NULL, UPDATE_FRAME);
+	AddAction(std::make_unique<CPActionUniquePatterns>(m_iTrack));
 }
 
 void CMainFrame::OnEditGoto()
diff --git a/Source/PatternAction.cpp b/Source/PatternAction.cpp
index 72e2365f..c1915a0e 100644
--- a/Source/PatternAction.cpp
+++ b/Source/PatternAction.cpp
@@ -1273,3 +1273,47 @@ void CPActionHighlight::UpdateView(CFamiTrackerDoc *pDoc) const
 {
 	pDoc->UpdateAllViews(NULL, UPDATE_HIGHLIGHT);
 }
+
+
+
+bool CPActionUniquePatterns::SaveState(const CMainFrame &MainFrm) {
+	const auto *pDoc = static_cast<CFamiTrackerView*>(MainFrm.GetActiveView())->GetDocument();
+	if (index_ >= pDoc->GetTrackCount())
+		return false;
+	const auto &Song = pDoc->GetSongData(index_);
+	const int Rows = Song.GetPatternLength();
+	const int Frames = Song.GetFrameCount();
+
+	songNew_ = std::make_unique<CSongData>(Rows);
+	songNew_->SetSongSpeed(Song.GetSongSpeed());
+	songNew_->SetSongTempo(Song.GetSongTempo());
+	songNew_->SetFrameCount(Frames);
+	songNew_->SetSongGroove(Song.GetSongGroove());
+	songNew_->SetTitle(Song.GetTitle());
+
+	for (int c = 0; c < pDoc->GetChannelCount(); c++) {
+		songNew_->SetEffectColumnCount(c, Song.GetEffectColumnCount(c));
+		for (int f = 0; f < Frames; f++) {
+			songNew_->SetFramePattern(f, c, f);
+			songNew_->GetPattern(c, f) = Song.GetPattern(c, Song.GetFramePattern(f, c));
+		}
+	}
+
+	return true;
+}
+
+void CPActionUniquePatterns::Undo(CMainFrame &MainFrm) const {
+	ASSERT(song_);
+	auto pDoc = static_cast<CFamiTrackerView*>(MainFrm.GetActiveView())->GetDocument();
+	songNew_ = pDoc->ReplaceSong(index_, std::move(song_));
+}
+
+void CPActionUniquePatterns::Redo(CMainFrame &MainFrm) const {
+	ASSERT(songNew_);
+	auto pDoc = static_cast<CFamiTrackerView*>(MainFrm.GetActiveView())->GetDocument();
+	song_ = pDoc->ReplaceSong(index_, std::move(songNew_));
+}
+
+void CPActionUniquePatterns::UpdateView(CFamiTrackerDoc *pDoc) const {
+	pDoc->UpdateAllViews(NULL, UPDATE_FRAME);
+}
diff --git a/Source/PatternAction.h b/Source/PatternAction.h
index 23e5b606..d001c29d 100644
--- a/Source/PatternAction.h
+++ b/Source/PatternAction.h
@@ -24,6 +24,7 @@
 #pragma once
 
 #include <vector>		// // //
+#include <memory>		// // //
 #include "Action.h"
 #include "PatternEditorTypes.h"
 #include "SongData.h"		// // //
@@ -79,7 +80,7 @@ class CPatternAction : public CAction
 public:
 	enum ACTIONS
 	{
-		ACT_EDIT_NOTE,
+		ACT_EDIT_NOTE = 1,
 		ACT_REPLACE_NOTE,		// // //
 		ACT_INSERT_ROW,
 		ACT_DELETE_ROW,
@@ -395,3 +396,17 @@ class CPActionHighlight : public CPatternAction		// // //
 private:
 	stHighlight m_OldHighlight, m_NewHighlight;
 };
+
+class CPActionUniquePatterns : public CPatternAction {
+public:
+	CPActionUniquePatterns(unsigned index) : CPatternAction(0), index_(index) { }
+private:
+	bool SaveState(const CMainFrame &MainFrm) override;
+	void Undo(CMainFrame &MainFrm) const override;
+	void Redo(CMainFrame &MainFrm) const override;
+	void UpdateView(CFamiTrackerDoc *pDoc) const;
+
+	mutable std::unique_ptr<CSongData> song_; // ???
+	mutable std::unique_ptr<CSongData> songNew_;
+	unsigned index_ = 0;
+};