diff --git a/ChangeLog b/ChangeLog
index dbf086e416..dc2e32c268 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,7 @@ phpMyAdmin - ChangeLog
 - bug #4744 Opening console scroll down the page
 - bug       Remove extra column heading in view structure page
 - bug       Add missing confirmation when deleting central columns
+- bug       Undefined index DisableIS
 
 4.3.9.0 (2015-02-05)
 - bug #4728 Incorrect headings in routine editor
diff --git a/libraries/navigation/Nodes/Node.class.php b/libraries/navigation/Nodes/Node.class.php
index d18783c39d..a067d30ff3 100644
--- a/libraries/navigation/Nodes/Node.class.php
+++ b/libraries/navigation/Nodes/Node.class.php
@@ -367,7 +367,9 @@ class Node
         $maxItems = $GLOBALS['cfg']['FirstLevelNavigationItems'];
         if ($GLOBALS['cfg']['NavigationTreeEnableGrouping']) {
             $dbSeparator = $GLOBALS['cfg']['NavigationTreeDbSeparator'];
-            if (! $GLOBALS['cfg']['Server']['DisableIS']) {
+            if (isset($GLOBALS['cfg']['Server']['DisableIS'])
+                && ! $GLOBALS['cfg']['Server']['DisableIS']
+            ) {
                 $query  = "SELECT `SCHEMA_NAME` ";
                 $query .= "FROM `INFORMATION_SCHEMA`.`SCHEMATA`, ";
                 $query .= "(";
@@ -472,7 +474,9 @@ class Node
                 }
             }
         } else {
-            if (! $GLOBALS['cfg']['Server']['DisableIS']) {
+            if (isset($GLOBALS['cfg']['Server']['DisableIS'])
+                && ! $GLOBALS['cfg']['Server']['DisableIS']
+            ) {
                 $query  = "SELECT `SCHEMA_NAME` ";
                 $query .= "FROM `INFORMATION_SCHEMA`.`SCHEMATA` ";
                 $query .= $this->_getWhereClause('SCHEMA_NAME', $searchClause);
@@ -538,7 +542,9 @@ class Node
     {
         if ($GLOBALS['cfg']['NavigationTreeEnableGrouping']) {
             $dbSeparator = $GLOBALS['cfg']['NavigationTreeDbSeparator'];
-            if (! $GLOBALS['cfg']['Server']['DisableIS']) {
+            if (isset($GLOBALS['cfg']['Server']['DisableIS'])
+                && ! $GLOBALS['cfg']['Server']['DisableIS']
+            ) {
                 $query = "SELECT COUNT(*) ";
                 $query .= "FROM ( ";
                 $query .= "SELECT DISTINCT SUBSTRING_INDEX(SCHEMA_NAME, ";
@@ -586,7 +592,9 @@ class Node
                 }
             }
         } else {
-            if (! $GLOBALS['cfg']['Server']['DisableIS']) {
+            if (isset($GLOBALS['cfg']['Server']['DisableIS'])
+                && ! $GLOBALS['cfg']['Server']['DisableIS']
+            ) {
                 $query = "SELECT COUNT(*) ";
                 $query .= "FROM INFORMATION_SCHEMA.SCHEMATA ";
                 $query .= $this->_getWhereClause('SCHEMA_NAME', $searchClause);