diff --git a/src/HistoryWindow.cpp b/src/HistoryWindow.cpp
index 0fd89c0f5..cfc2a2c1e 100644
--- a/src/HistoryWindow.cpp
+++ b/src/HistoryWindow.cpp
@@ -38,6 +38,7 @@ undo memory so as to free up space.
 
 enum {
    ID_AVAIL = 1000,
+   ID_TOTAL,
    ID_LEVELS,
    ID_DISCARD
 };
@@ -71,7 +72,7 @@ HistoryWindow::HistoryWindow(AudacityProject *parent, UndoManager *manager):
    S.SetBorder(5);
    S.StartVerticalLay(true);
    {
-      S.StartStatic(_("Manage History"), 1);
+      S.StartStatic(_("&Manage History"), 1);
       {
          mList = S.AddListControlReportMode();
          // Do this BEFORE inserting the columns.  On the Mac at least, the
@@ -85,13 +86,15 @@ HistoryWindow::HistoryWindow(AudacityProject *parent, UndoManager *manager):
 
          S.StartMultiColumn(3, wxCENTRE);
          {
+            mTotal = S.Id(ID_TOTAL).AddTextBox(_("&Total space used"), wxT("0"), 10);
+            mTotal->Connect(wxEVT_KEY_DOWN, wxKeyEventHandler(HistoryWindow::OnChar));
+            S.AddVariableText(wxT(""))->Hide();
+
             mAvail = S.Id(ID_AVAIL).AddTextBox(_("&Undo Levels Available"), wxT("0"), 10);
             mAvail->Connect(wxEVT_KEY_DOWN, wxKeyEventHandler(HistoryWindow::OnChar));
             S.AddVariableText(wxT(""))->Hide();
-         }
 
-         {
-            S.AddPrompt(_("Levels To Discard"));
+            S.AddPrompt(_("&Levels To Discard"));
             mLevels = new wxSpinCtrl(this,
                                      ID_LEVELS,
                                      wxT("1"),
@@ -146,15 +149,18 @@ void HistoryWindow::DoUpdate()
 
    mList->DeleteAllItems();
 
+   wxLongLong_t total = 0;
    mSelected = mManager->GetCurrentState() - 1;
    for (i = 0; i < (int)mManager->GetNumStates(); i++) {
       wxString desc, size;
 
-      mManager->GetLongDescription(i + 1, &desc, &size);
+      total += mManager->GetLongDescription(i + 1, &desc, &size);
       mList->InsertItem(i, desc, i == mSelected ? 1 : 0);
       mList->SetItem(i, 1, size);
    }
 
+   mTotal->SetValue(Internat::FormatSize(total));
+
    mList->EnsureVisible(mSelected);
 
    mList->SetItemState(mSelected,
diff --git a/src/HistoryWindow.h b/src/HistoryWindow.h
index f14a1f33e..8ee5c69b5 100644
--- a/src/HistoryWindow.h
+++ b/src/HistoryWindow.h
@@ -44,6 +44,7 @@ class HistoryWindow :public wxDialog {
    AudacityProject   *mProject;
    UndoManager       *mManager;
    wxListCtrl        *mList;
+   wxTextCtrl        *mTotal;
    wxTextCtrl        *mAvail;
    wxSpinCtrl        *mLevels;
    wxButton          *mDiscard;
diff --git a/src/UndoManager.cpp b/src/UndoManager.cpp
index ba37f20b7..0c9ecfd9c 100644
--- a/src/UndoManager.cpp
+++ b/src/UndoManager.cpp
@@ -87,7 +87,7 @@ void UndoManager::CalculateSpaceUsage()
 
                // Accumulate space used by the file if the file didn't exist
                // in the previous level
-               if (!prev->count(file))
+               if (prev->count(file) == 0 && cur->count(file) == 0)
                {
                   space[i] += file->GetSpaceUsage().GetValue();
                }
@@ -108,8 +108,8 @@ void UndoManager::CalculateSpaceUsage()
    TIMER_STOP( space_calc );
 }
 
-void UndoManager::GetLongDescription(unsigned int n, wxString *desc,
-                                     wxString *size)
+wxLongLong_t UndoManager::GetLongDescription(unsigned int n, wxString *desc,
+                                             wxString *size)
 {
    n -= 1; // 1 based to zero based
 
@@ -119,6 +119,8 @@ void UndoManager::GetLongDescription(unsigned int n, wxString *desc,
    *desc = stack[n]->description;
 
    *size = Internat::FormatSize(space[n]);
+
+   return space[n];
 }
 
 void UndoManager::GetShortDescription(unsigned int n, wxString *desc)
diff --git a/src/UndoManager.h b/src/UndoManager.h
index 5eb3ef80b..c646fa117 100644
--- a/src/UndoManager.h
+++ b/src/UndoManager.h
@@ -64,7 +64,9 @@ struct UndoStackElem {
 };
 
 WX_DEFINE_USER_EXPORTED_ARRAY(UndoStackElem *, UndoStack, class AUDACITY_DLL_API);
-WX_DEFINE_USER_EXPORTED_ARRAY_SIZE_T(size_t, SpaceArray, class AUDACITY_DLL_API);
+// wxWidgets arrays have a base size and to use wxLongLong_t we need to use DOUBLE
+// to ensure we get a size big enough to hold a wxLongLong_t.
+WX_DEFINE_USER_EXPORTED_ARRAY_DOUBLE(wxLongLong_t, SpaceArray, class AUDACITY_DLL_API);
 
 // These flags control what extra to do on a PushState
 // Default is PUSH_AUTOSAVE
@@ -91,7 +93,7 @@ class AUDACITY_DLL_API UndoManager {
    unsigned int GetCurrentState();
 
    void GetShortDescription(unsigned int n, wxString *desc);
-   void GetLongDescription(unsigned int n, wxString *desc, wxString *size);
+   wxLongLong_t GetLongDescription(unsigned int n, wxString *desc, wxString *size);
    void SetLongDescription(unsigned int n, wxString desc);
 
    TrackList *SetStateTo(unsigned int n, SelectedRegion *selectedRegion);