diff --git a/src/HistoryWindow.cpp b/src/HistoryWindow.cpp
index ec37b3850..e6c824e60 100644
--- a/src/HistoryWindow.cpp
+++ b/src/HistoryWindow.cpp
@@ -43,6 +43,8 @@ undo memory so as to free up space.
 #include "ProjectFileIO.h"
 #include "ProjectHistory.h"
 #include "ShuttleGui.h"
+#include "widgets/AudacityMessageBox.h"
+#include "widgets/HelpSystem.h"
 
 enum {
    ID_AVAIL = 1000,
@@ -50,7 +52,8 @@ enum {
    ID_TOTAL,
    ID_LEVELS,
    ID_DISCARD,
-   ID_DISCARD_CLIPBOARD
+   ID_DISCARD_CLIPBOARD,
+   ID_COMPACT
 };
 
 BEGIN_EVENT_TABLE(HistoryDialog, wxDialogWrapper)
@@ -59,6 +62,8 @@ BEGIN_EVENT_TABLE(HistoryDialog, wxDialogWrapper)
    EVT_LIST_ITEM_SELECTED(wxID_ANY, HistoryDialog::OnItemSelected)
    EVT_BUTTON(ID_DISCARD, HistoryDialog::OnDiscard)
    EVT_BUTTON(ID_DISCARD_CLIPBOARD, HistoryDialog::OnDiscardClipboard)
+   EVT_BUTTON(ID_COMPACT, HistoryDialog::OnCompact)
+   EVT_BUTTON(wxID_HELP, HistoryDialog::OnGetURL)
 END_EVENT_TABLE()
 
 HistoryDialog::HistoryDialog(AudacityProject *parent, UndoManager *manager):
@@ -126,19 +131,15 @@ HistoryDialog::HistoryDialog(AudacityProject *parent, UndoManager *manager):
 
             mClipboard = S
                .ConnectRoot(wxEVT_KEY_DOWN, &HistoryDialog::OnChar)
-               .AddTextBox(XXO("Clipboard space used"), wxT("0"), 10);
-            S.Id(ID_DISCARD_CLIPBOARD).AddButton(XXO("Discard"));
+               .AddTextBox(XXO("Clip&board space used"), wxT("0"), 10);
+            S.Id(ID_DISCARD_CLIPBOARD).AddButton(XXO("D&iscard"));
          }
          S.EndMultiColumn();
       }
       S.EndStatic();
 
-      S.StartHorizontalLay(wxALIGN_RIGHT, false);
-      {
-         S.SetBorder(10);
-         S.Id(wxID_OK).AddButton(XXO("&OK"), wxALIGN_CENTER, true);
-      }
-      S.EndHorizontalLay();
+      mCompact = safenew wxButton(this, ID_COMPACT, _("&Compact"));
+      S.AddStandardButtons(eOkButton | eHelpButton, mCompact);
    }
    S.EndVerticalLay();
    // ----------------------- End of main section --------------
@@ -179,6 +180,7 @@ void HistoryDialog::OnAudioIO(wxCommandEvent& evt)
       mAudioIOBusy = false;
 
    mDiscard->Enable(!mAudioIOBusy);
+   mCompact->Enable(!mAudioIOBusy);
 }
 
 void HistoryDialog::UpdateDisplay(wxEvent& e)
@@ -274,6 +276,31 @@ void HistoryDialog::OnDiscardClipboard(wxCommandEvent & WXUNUSED(event))
    Clipboard::Get().Clear();
 }
 
+void HistoryDialog::OnCompact(wxCommandEvent & WXUNUSED(event))
+{
+   auto &projectFileIO = ProjectFileIO::Get(*mProject);
+
+   projectFileIO.ReopenProject();
+
+   auto baseFile = wxFileName(projectFileIO.GetFileName());
+   auto walFile = wxFileName(projectFileIO.GetFileName() + wxT("-wal"));
+   auto before = baseFile.GetSize() + walFile.GetSize();
+
+   projectFileIO.Compact(nullptr, true);
+
+   auto after = baseFile.GetSize() + walFile.GetSize();
+
+   AudacityMessageBox(
+      XO("Compacting actually freed %s of disk space.")
+      .Format(Internat::FormatSize((before - after).GetValue())),
+      XO("History"));
+}
+
+void HistoryDialog::OnGetURL(wxCommandEvent & WXUNUSED(event))
+{
+   HelpSystem::ShowHelp(this, wxT("View_Menu#history"));
+}
+
 void HistoryDialog::OnItemSelected(wxListEvent &event)
 {
    if (mAudioIOBusy) {
diff --git a/src/HistoryWindow.h b/src/HistoryWindow.h
index e86eb3fc6..87b0a7481 100644
--- a/src/HistoryWindow.h
+++ b/src/HistoryWindow.h
@@ -42,6 +42,8 @@ class HistoryDialog final : public wxDialogWrapper {
    void OnItemSelected(wxListEvent & event);
    void OnDiscard(wxCommandEvent & event);
    void OnDiscardClipboard(wxCommandEvent & event);
+   void OnCompact(wxCommandEvent & event);
+   void OnGetURL(wxCommandEvent & event);
 
    AudacityProject   *mProject;
    UndoManager       *mManager;
@@ -51,6 +53,7 @@ class HistoryDialog final : public wxDialogWrapper {
    wxTextCtrl        *mAvail;
    wxSpinCtrl        *mLevels;
    wxButton          *mDiscard;
+   wxButton          *mCompact;
 
    int               mSelected;
    bool              mAudioIOBusy;
diff --git a/src/ProjectFileIO.cpp b/src/ProjectFileIO.cpp
index 307b1c4c3..6345c55b7 100644
--- a/src/ProjectFileIO.cpp
+++ b/src/ProjectFileIO.cpp
@@ -1022,8 +1022,9 @@ void ProjectFileIO::Compact(const std::shared_ptr<TrackList> &tracks, bool force
    wxString backName = origName + "_compact_back";
    wxString tempName = origName + "_compact_temp";
 
-   // Copy the original database to a new database while pruning unused sample blocks
-   if (CopyTo(tempName, XO("Compacting project"), mTemporary, true, tracks))
+   // Copy the original database to a new database. Only prune sample blocks if
+   // we have a tracklist.
+   if (CopyTo(tempName, XO("Compacting project"), mTemporary, tracks != nullptr, tracks))
    {
       // Must close the database to rename it
       if (CloseConnection())