--- a/browser/base/content/newtab/sites.js
+++ b/browser/base/content/newtab/sites.js
@@ -139,17 +139,17 @@ Site.prototype = {
 
   /**
    * Adds event handlers for the site and its buttons.
    */
   _addEventHandlers: function Site_addEventHandlers() {
     // Register drag-and-drop event handlers.
     this._node.addEventListener("dragstart", this, false);
     this._node.addEventListener("dragend", this, false);
-    this._node.addEventListener("mouseenter", this, false);
+    this._node.addEventListener("mouseover", this, false);
 
     let controls = this.node.querySelectorAll(".newtab-control");
     for (let i = 0; i < controls.length; i++)
       controls[i].addEventListener("click", this, false);
   },
 
   /**
    * Speculatively opens a connection to the current site.
@@ -169,17 +169,18 @@ Site.prototype = {
         aEvent.preventDefault();
         if (aEvent.target.classList.contains("newtab-control-block"))
           this.block();
         else if (this.isPinned())
           this.unpin();
         else
           this.pin();
         break;
-      case "mouseenter":
+      case "mouseover":
+        this._node.removeEventListener("mouseover", this, false);
         this._speculativeConnect();
         break;
       case "dragstart":
         gDrag.start(this, aEvent);
         break;
       case "drag":
         gDrag.drag(this, aEvent);
         break;