diff --git a/content/treestyletab/bookmarksOverlay.js b/content/treestyletab/bookmarksOverlay.js
index d9a1ce0e..901f5a89 100644
--- a/content/treestyletab/bookmarksOverlay.js
+++ b/content/treestyletab/bookmarksOverlay.js
@@ -277,10 +277,14 @@ var TreeStyleTabBookmarksService = {
 								else {
 									sv.readyToOpenNewTabGroup(null, treeStructure, TSTOpenGroupBookmarkBehavior & sv.kGROUP_BOOKMARK_EXPAND_ALL_TREE);
 								}
-								replaceCurrentTab = false;
+								// replaceCurrentTab works only on Firefox 7 or earlier
+								// See: https://bugzilla.mozilla.org/show_bug.cgi?id=440093
+								if (typeof replaceCurrentTab !== 'undefined')
+									replaceCurrentTab = false;
 							}
 							else {
-								replaceCurrentTab = !!(TSTOpenGroupBookmarkBehavior & sv.kGROUP_BOOKMARK_REPLACE);
+								if (typeof replaceCurrentTab !== 'undefined')
+									replaceCurrentTab = !!(TSTOpenGroupBookmarkBehavior & sv.kGROUP_BOOKMARK_REPLACE);
 							}
 						}
 						$1
diff --git a/content/treestyletab/config.js b/content/treestyletab/config.js
index a97a9396..f4a055a1 100644
--- a/content/treestyletab/config.js
+++ b/content/treestyletab/config.js
@@ -168,6 +168,16 @@ function initTabPane()
 		newTabPref.removeAttribute('hidden');
 	else
 		newTabPref.setAttribute('hidden', true);
+
+	var bookmarkGroupReplacePref = document.getElementById('openGroupBookmark.replace');
+	if (comparator.compare(XULAppInfo.version, '7.0') > 0) {
+		if (bookmarkGroupReplacePref.selected)
+			document.getElementById('openGroupBookmark.subtree').selected = true;
+		bookmarkGroupReplacePref.setAttribute('hidden', true);
+	}
+	else {
+		bookmarkGroupReplacePref.removeAttribute('hidden');
+	}
 }
 
 function onSyncGroupBookmarkUIToPref()
diff --git a/content/treestyletab/config.xul b/content/treestyletab/config.xul
index 1b8358f5..f764145e 100644
--- a/content/treestyletab/config.xul
+++ b/content/treestyletab/config.xul
@@ -446,7 +446,7 @@
 				onsyncfrompreference="return onSyncGroupBookmarkPrefToUI();"
 				preference="extensions.treestyletab.openGroupBookmark.behavior">
 				<radio value="0" collapsed="true"/>
-				<radio value="1" label="&config.openGroupBookmark.subtree;"/>
+				<radio id="openGroupBookmark.subtree" value="1" label="&config.openGroupBookmark.subtree;"/>
 				<hbox>
 					<spacer style="width:1em;"/>
 					<vbox>
@@ -471,7 +471,8 @@
 					</vbox>
 				</hbox>
 				<radio value="2" label="&config.openGroupBookmark.flat;"/>
-				<radio value="4" label="&config.openGroupBookmark.replace;"/>
+				<radio id="openGroupBookmark.replace"
+					value="4" label="&config.openGroupBookmark.replace;"/>
 			</radiogroup>
 			</vbox>
 		</deck>