diff --git a/js/models/lattice.js b/js/models/lattice.js
index 5d414822bd8d0d8ee59b2b197a52df1274cf03b5..31b6a4e7257f514ff8170c7dde3cba2756ca3a9d 100644
--- a/js/models/lattice.js
+++ b/js/models/lattice.js
@@ -60,7 +60,7 @@ Lattice = Backbone.Model.extend({
         }
 
         var index = this._subtract(position, this.get("cellsMin"));
-        cells[index.x][index.y][index.z] = new DMACell(this.get("cellMode"), position, scale);
+        if (!cells[index.x][index.y][index.z]) cells[index.x][index.y][index.z] = new DMACell(this.get("cellMode"), position, scale);
         this.set("numCells", this.get("numCells")+1);
         window.three.render();
     },
diff --git a/js/threeViews/threeView.js b/js/threeViews/threeView.js
index 00f3b6e66d1be0b1f90a8150ef2b438f641ca841..6e5c4774688e6ffc1ca65ae2fb595a7d010abf87 100644
--- a/js/threeViews/threeView.js
+++ b/js/threeViews/threeView.js
@@ -80,7 +80,7 @@ ThreeView = Backbone.View.extend({
 
     _mouseUp: function(){
         this.mouseIsDown = false;
-        if (this.highlighter.visible) this._addRemoveVoxel(!this.appState.get("deleteMode"));
+        this._addRemoveVoxel(!this.appState.get("deleteMode"));
     },
 
     _mouseDown: function(){
@@ -179,7 +179,7 @@ ThreeView = Backbone.View.extend({
     _addRemoveVoxel: function(shouldAdd){
 
         if (shouldAdd){
-//            if (!this.highlighter.visible) return;
+            if (!this.highlighter.visible) return;
             this.lattice.addCell(this.highlighter.geometry.vertices[0]);
         } else {
             if (this.currentIntersectedCell === this.basePlane) return;