diff --git a/XSVim/Addin.fs b/XSVim/Addin.fs
index e448f47..d0e147e 100644
--- a/XSVim/Addin.fs
+++ b/XSVim/Addin.fs
@@ -8,7 +8,6 @@ open MonoDevelop.Ide
 open MonoDevelop.Ide.Editor
 open MonoDevelop.Ide.Editor.Extension
 open MonoDevelop.Ide.FindInFiles
-open MonoDevelop.Ide.Gui.Components
 open Reflection
 
 module Subscriptions =
@@ -74,11 +73,11 @@ type XSVim() as this =
         KeyDescriptor.FromGtk(Enum.Parse(typeof<Gdk.Key>, c) :?> Gdk.Key, char c, Gdk.ModifierType.ControlMask)
         |> this.KeyPress
 
-    member x.FileName = x.Editor.FileName.FullPath
+    let mutable fileName = FilePath.Empty
 
     member x.State
-        with get() = Vim.editorStates.[x.FileName]
-        and set(value) = Vim.editorStates.[x.FileName] <- value
+        with get() = Vim.editorStates.[fileName]
+        and set(value) = Vim.editorStates.[fileName] <- value
 
 
     override x.IsValidInContext documentContext =
@@ -87,10 +86,10 @@ type XSVim() as this =
     override x.Initialize() =
         treeViewPads.initialize()
         x.Editor.FocusLost.Add(fun _ -> initializeSearchResultsPads())
-
-        LoggingService.LogDebug("XSVim initializing - " + string x.FileName)
+        fileName <- x.Editor.FileName.FullPath
+        LoggingService.LogDebug("XSVim initializing - " + string fileName)
         initConfig()
-        if not (Vim.editorStates.ContainsKey x.FileName) then
+        if not (Vim.editorStates.ContainsKey fileName) then
             let editor = x.Editor
             let state =
                 match Vim.getCaretMode editor with
@@ -98,7 +97,7 @@ type XSVim() as this =
                 | Block -> VimState.Default
 
             let initialState = Vim.switchToNormalMode editor state
-            Vim.editorStates.Add(x.FileName, initialState)
+            Vim.editorStates.Add(fileName, initialState)
             editor.GrabFocus()
             let caretChanged =
                 editor.CaretPositionChanged.Subscribe
@@ -147,9 +146,6 @@ type XSVim() as this =
             x.Editor.ClearSelection()
             false
         | ModifierKeys.Command when descriptor.KeyChar <> 'z' && descriptor.KeyChar <> 'r' -> false
-        | _ when isNull x.Editor ->
-            // Seems like we can get into this state when closing a tab
-            false
         | _ ->
             let oldState = x.State
 
diff --git a/XSVim/Properties/AssemblyInfo.fs b/XSVim/Properties/AssemblyInfo.fs
index 733c06e..d5ed864 100644
--- a/XSVim/Properties/AssemblyInfo.fs
+++ b/XSVim/Properties/AssemblyInfo.fs
@@ -5,7 +5,7 @@ open System.Runtime.CompilerServices
 [<AutoOpen>]
 module AddinVersion =
     [<Literal>]
-    let version = "0.63.2"
+    let version = "0.63.3"
 
 [<assembly: AssemblyTitle("XSVim")>]
 // The assembly version has the format {Major}.{Minor}.{Build}.{Revision}
diff --git a/XSVim/WindowManagement.fs b/XSVim/WindowManagement.fs
index 671f87f..05e3584 100644
--- a/XSVim/WindowManagement.fs
+++ b/XSVim/WindowManagement.fs
@@ -85,11 +85,12 @@ module Window =
             switchToNotebook notebooks.[1]
 
     let closeTab() =
-        match tryActiveInactiveNoteBooks() with
+        let n = tryActiveInactiveNoteBooks()
+        match n with
         | Some active, Some inactive when active.tabs.Length = 1 ->
             dispatch FileCommands.CloseFile
             switchToNotebook inactive
-        | Some active, _ when active.tabs.Length > 1 ->
+        | Some active, _ when active.activeTab > 0 ->
             dispatch FileCommands.CloseFile
             openDocument active.tabs.[active.activeTab-1]
         | _ -> dispatch FileCommands.CloseFile
diff --git a/XSVim/XSVim.fs b/XSVim/XSVim.fs
index 8246d19..14f539f 100755
--- a/XSVim/XSVim.fs
+++ b/XSVim/XSVim.fs
@@ -856,7 +856,12 @@ module Vim =
                 if editor.SelectionMode = SelectionMode.Normal then EditActions.ToggleBlockSelectionMode editor
                 switchToInsertMode editor vimState isInitial
 
-            let start, finish = VimHelpers.getRange vimState editor command
+            let start, finish =
+                if editor.Length > 0 then
+                    VimHelpers.getRange vimState editor command
+                else
+                    // editor can have zero length when a tab containing it has just been closed
+                    0, 0
 
             let newState =
                 match command.commandType with
@@ -1702,7 +1707,8 @@ module Vim =
             | SpecialKey.Delete -> VimKey.Delete
             | _ -> Key keyPress.KeyChar
 
-    let handleKeyPress state (keyPress:KeyDescriptor) editor config =
+    let handleKeyPress state (keyPress:KeyDescriptor) (editor:TextEditor) config =
+        let fileName = editor.FileName
         let vimKey =
             match state.mode, keyPress.KeyChar, config.insertModeEscapeKey with
             | InsertMode, c, Some combo when (string c) = combo.insertModeEscapeKey1 ->
@@ -1769,5 +1775,6 @@ module Vim =
             | NotInsertMode, Key 'O', _
             | NotInsertMode, Key 'A', _ -> { newState with lastAction = action }
             | _ -> newState
-        editorStates.[editor.FileName] <- newState
+
+        editorStates.[fileName] <- newState
         newState, handled