diff --git a/mobile/android/chrome/content/browser.js b/mobile/android/chrome/content/browser.js
index c01b243c9108..cabdf47be282 100644
--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -3428,6 +3428,7 @@ function Tab(aURL, aParams) {
   this.filter = null;
   this.browser = null;
   this.id = 0;
+  this._parentId = -1;
   this.lastTouchedAt = Date.now();
   this._zoom = 1.0;
   this._drawZoom = 1.0;
@@ -3555,7 +3556,7 @@ Tab.prototype = {
       }
 
       this.desktopMode = ("desktopMode" in aParams) ? aParams.desktopMode : false;
-      this.parentId = ("parentId" in aParams && typeof aParams.parentId == "number")
+      this._parentId = ("parentId" in aParams && typeof aParams.parentId == "number")
                       ? aParams.parentId : -1;
 
       let message = {
@@ -3959,9 +3960,13 @@ Tab.prototype = {
     }
   },
 
-  setParentId: function(aParentId) {
+  get parentId() {
+    return this._parentId;
+  },
+
+  set parentId(aParentId) {
     let newParentId = (typeof aParentId == "number") ? aParentId : -1;
-    this.parentId = newParentId;
+    this._parentId = newParentId;
     GlobalEventDispatcher.sendRequest({
       type: "Tab:SetParentId",
       tabID: this.id,
diff --git a/mobile/android/components/SessionStore.js b/mobile/android/components/SessionStore.js
index d9517f54e6de..6d555ef6b074 100644
--- a/mobile/android/components/SessionStore.js
+++ b/mobile/android/components/SessionStore.js
@@ -1640,7 +1640,7 @@ SessionStore.prototype = {
 
       let parentId = tabData.parentId;
       if (parentId > -1) {
-        tab.setParentId(parentId);
+        tab.parentId = parentId;
       }
 
       tab.browser.__SS_data = tabData;