diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index 66058b93d..cee9ae538 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -1209,14 +1209,18 @@ const Workspace = new Lang.Class({
         return this._windows.length == 0;
     },
 
-    setReservedSlot: function(clone) {
-        if (this._reservedSlot == clone)
+    setReservedSlot: function(metaWindow) {
+        if (this._reservedSlotWindow == metaWindow)
             return;
 
-        if (clone && this.containsMetaWindow(clone.metaWindow))
-            clone = null;
+        if (!metaWindow || this.containsMetaWindow(metaWindow)) {
+            this._reservedSlotWindow = null;
+            this._reservedSlot = null;
+        } else {
+            this._reservedSlotWindow = metaWindow;
+            this._reservedSlot = this._windows[this._lookupIndex(metaWindow)];
+        }
 
-        this._reservedSlot = clone;
         this._recalculateWindowPositions(WindowPositionFlags.ANIMATE);
     },
 
diff --git a/js/ui/workspacesView.js b/js/ui/workspacesView.js
index 004ac81ae..9e75661f6 100644
--- a/js/ui/workspacesView.js
+++ b/js/ui/workspacesView.js
@@ -65,7 +65,7 @@ const WorkspacesViewBase = new Lang.Class({
 
     _dragBegin: function(overview, clone) {
         this._inDrag = true;
-        this._setReservedSlot(clone);
+        this._setReservedSlot(clone.metaWindow);
     },
 
     _dragEnd: function() {
@@ -127,9 +127,9 @@ const WorkspacesView = new Lang.Class({
                                           Lang.bind(this, this._activeWorkspaceChanged));
     },
 
-    _setReservedSlot: function(clone) {
+    _setReservedSlot: function(window) {
         for (let i = 0; i < this._workspaces.length; i++)
-            this._workspaces[i].setReservedSlot(clone);
+            this._workspaces[i].setReservedSlot(window);
     },
 
     _syncFullGeometry: function() {
@@ -366,8 +366,8 @@ const ExtraWorkspaceView = new Lang.Class({
         this.actor.add_actor(this._workspace.actor);
     },
 
-    _setReservedSlot: function(clone) {
-        this._workspace.setReservedSlot(clone);
+    _setReservedSlot: function(window) {
+        this._workspace.setReservedSlot(window);
     },
 
     _syncFullGeometry: function() {