diff --git a/src/actions.nim b/src/actions.nim
index 546d874e..fa727af2 100644
--- a/src/actions.nim
+++ b/src/actions.nim
@@ -40,7 +40,8 @@ template cellAreaAction(map; loc, undoLoc: Location, rect: Rect[Natural];
 
   var oldLinks = map.links
 
-  let undoLevel = map.newLevelFrom(loc.levelId, rect)
+  let undoLevel = map.newLevelFrom(loc.levelId, rect,
+                                   overrideId=0.Natural.some)
 
   let undoAction = proc (m: var Map): UndoStateData =
     m.levels[loc.levelId].copyCellsAndAnnotationsFrom(
@@ -327,7 +328,8 @@ proc setLink*(map; src, dest: Location, floorColor: Natural; um) =
     c = dest.col
     rect = rectN(r, c, r+1, c+1)  # single cell
 
-  let undoLevel = map.newLevelFrom(dest.levelId, rect)
+  let undoLevel = map.newLevelFrom(dest.levelId, rect,
+                                   overrideId=0.Natural.some)
 
   var oldLinks = initLinks()
 
@@ -686,6 +688,7 @@ proc addNewLevel*(map; loc: Location,
   # Undo action
   let undoAction = proc (m: var Map): UndoStateData =
     m.delLevel(newLevelId)
+    setNextLevelId(newLevelId)
 
     for src in m.links.filterByLevel(newLevelId).sources:
       m.links.delBySrc(src)
@@ -904,6 +907,7 @@ proc nudgeLevel*(map; loc: Location, rowOffs, colOffs: int,
 
   # Do action
   let action = proc (m: var Map): UndoStateData =
+
     # Propagate ID as this is the same level, just nudged
     var l = newLevel(
       sb.level.locationName, sb.level.levelName, sb.level.elevation,
diff --git a/src/level.nim b/src/level.nim
index 41eb1686..e14f162b 100644
--- a/src/level.nim
+++ b/src/level.nim
@@ -476,9 +476,14 @@ proc isSpecialLevelId*(id: Natural): bool =
 
 # }}}
 
-# {{{ newLevel*()
+# {{{ setNextLevelId*()
+var g_nextLevelId = 0
+
+proc setNextLevelId*(nextId: Natural) =
+  g_nextLevelId = nextId
 
-var g_levelIdCounter = 0
+# }}}
+# {{{ newLevel*()
 
 const DefaultCoordOpts = CoordinateOptions(
   origin:      coNorthWest,
@@ -509,8 +514,8 @@ proc newLevel*(locationName, levelName: string, elevation: int,
   if overrideId.isSome:
     l.id = overrideId.get
   else:
-    l.id = g_levelIdCounter
-    inc(g_levelIdCounter)
+    l.id = g_nextLevelId
+    inc(g_nextLevelId)
 
   l.locationName = locationName
   l.levelName    = levelName
diff --git a/src/main.nim b/src/main.nim
index 15e32d3f..1a2480ac 100644
--- a/src/main.nim
+++ b/src/main.nim
@@ -4094,6 +4094,8 @@ proc newMapDialog(dlg: var NewMapDialogParams; a) =
 
     a.opts.drawTrail = false
 
+    setNextLevelId(0)
+
     a.doc.path = ""
     a.doc.map = newMap(dlg.title, dlg.game, dlg.author,
                        creationTime=now().format("yyyy-MM-dd HH:mm:ss"))
diff --git a/src/persistence.nim b/src/persistence.nim
index f7f859da..03599207 100644
--- a/src/persistence.nim
+++ b/src/persistence.nim
@@ -519,7 +519,7 @@ proc readLinks(
 
 # }}}
 # {{{ readLevelProperties()
-proc readLevelProperties(rr; levelId: Natural): Level =
+proc readLevelProperties(rr): Level =
   debug(fmt"Reading level properties...")
   pushDebugIndent()
 
@@ -545,8 +545,7 @@ proc readLevelProperties(rr; levelId: Natural): Level =
   let notes = rr.readWStr
   checkStringLength(notes, "lvl.prop.notes", NotesLimits)
 
-  result = newLevel(locationName, levelName, elevation, numRows, numColumns,
-                    overrideId = levelId.some)
+  result = newLevel(locationName, levelName, elevation, numRows, numColumns)
   result.overrideCoordOpts = overrideCoordOpts.bool
   result.notes = notes
 
@@ -820,7 +819,7 @@ proc readLevelRegions(rr; levelCols: Natural,
 
 # }}}
 # {{{ readLevel()
-proc readLevel(rr; levelId: Natural; version: Natural): Level =
+proc readLevel(rr; version: Natural): Level =
   debug(fmt"Reading level...")
   pushDebugIndent()
 
@@ -881,7 +880,7 @@ proc readLevel(rr; levelId: Natural; version: Natural): Level =
   if cellCursor.isNone: chunkNotFoundError(FourCC_GRMM_cell)
 
   rr.cursor = propCursor.get
-  var level = readLevelProperties(rr, levelId)
+  var level = readLevelProperties(rr)
 
   rr.cursor = coorCursor.get
   level.coordOpts = readCoordinateOptions(rr, groupChunkId.get)
@@ -911,7 +910,6 @@ proc readLevelList(rr; version: Natural): OrderedTable[Natural, Level] =
   pushDebugIndent()
 
   var levels = initOrderedTable[Natural, Level]()
-  var levelId = 0
 
   if rr.hasSubChunks:
     var ci = rr.enterGroup
@@ -927,9 +925,8 @@ proc readLevelList(rr; version: Natural): OrderedTable[Natural, Level] =
 
           # The level IDs must be set to their indices in the map file to
           # ensure they are in sync with link (see writeLinks()).
-          let level = readLevel(rr, levelId, version)
-          levels[levelId] = level
-          inc(levelId)
+          let level = readLevel(rr, version)
+          levels[level.id] = level
 
           rr.exitGroup
         else:
@@ -1134,10 +1131,12 @@ proc readMapFile*(path: string): tuple[map: Map,
     elif appStateGroupCursor.isSome:
       rr.cursor = appStateGroupCursor.get
       readAppState_V4(rr, map).some
-
     else:
       AppState.none
 
+    # Level IDs start from zero when loading a map
+    setNextLevelId(map.levels.len)
+
     result = (map, appState, warning)
 
   except MapReadError as e:
diff --git a/src/undomanager.nim b/src/undomanager.nim
index aca3bd52..a49d1599 100644
--- a/src/undomanager.nim
+++ b/src/undomanager.nim
@@ -68,7 +68,7 @@ proc undo*[S, R](m: var UndoManager[S, R], s: var S): R =
     let undoNextState = m.states[m.currState].groupWithPrev
     dec(m.currState)
     if undoNextState:
-      discard m.undo(s)
+      result = m.undo(s)
 
 # }}}