diff --git a/js/pMap.js b/js/pMap.js
index fc3f73849..bfcd4d235 100644
--- a/js/pMap.js
+++ b/js/pMap.js
@@ -23,6 +23,12 @@
 
 var imageMap = {
     'mouseMoved': function(event, cont) {
+        // return if no imageMap set
+        // this can happen if server has no json
+        if (!this.imageMap) {
+            return;
+        }
+        
         // get mouse coordinated relative to image
         var mouseX = event.pageX - cont.offsetLeft;
         var mouseY = event.pageY - cont.offsetTop;
diff --git a/libraries/chart.lib.php b/libraries/chart.lib.php
index 3939e552e..b8213f2ad 100644
--- a/libraries/chart.lib.php
+++ b/libraries/chart.lib.php
@@ -1,7 +1,7 @@
 <?php
 
 define('ERR_NO_GD', 0);
-define('ERR_UNKNOWN_FORMAT', 1);
+define('ERR_NO_JSON', 1);
 
 require_once './libraries/chart/pma_pchart_pie.php';
 require_once './libraries/chart/pma_pchart_single_bar.php';
@@ -66,7 +66,7 @@ function PMA_chart_profiling($data)
 /*
  * Formats a chart for query results page.
  */
-function PMA_chart_results($data, &$chartSettings, &$chartErrors = array())
+function PMA_chart_results($data, &$chartSettings)
 {
     $chartData = array();
     $chart = null;
@@ -103,7 +103,7 @@ function PMA_chart_results($data, &$chartSettings, &$chartErrors = array())
     }
 
     if (count($data[0]) == 1 || count($data[0]) == 2) {
-        // Two columns in every row.
+        // One or two columns in every row.
         // This data is suitable for a simple bar chart.
 
         if ($chartSettings['type'] == 'pie') {
@@ -220,14 +220,13 @@ function PMA_chart_results($data, &$chartSettings, &$chartErrors = array())
         }
     }
     else {
-        // unknown data
-        array_push($chartErrors, ERR_UNKNOWN_FORMAT);
+        // unknown data format
         return '';
     }
 
     $chartCode = $chart->toString();
     $chartSettings = $chart->getSettings();
-    $chartErrors = array_merge($chartErrors, $chart->getErrors());
+    $chartErrors = $chart->getErrors();
     PMA_handle_chart_err($chartErrors);
     
     return $chartCode;
@@ -241,6 +240,9 @@ function PMA_handle_chart_err($errors)
     if (in_array(ERR_NO_GD, $errors)) {
         PMA_warnMissingExtension('GD', false, 'GD extension is needed for charts.');
     }
+    else if (in_array(ERR_NO_JSON, $errors)) {
+        PMA_warnMissingExtension('JSON', false, 'JSON encoder is needed for chart tooltips.');
+    }
 }
 
 ?>
diff --git a/libraries/chart/pChart/pChart.class b/libraries/chart/pChart/pChart.class
index eb2bc4693..2b5a07721 100644
--- a/libraries/chart/pChart/pChart.class
+++ b/libraries/chart/pChart/pChart.class
@@ -3495,7 +3495,7 @@
    /* Get the current image map */
    function getImageMap()
    {
-    return json_encode($this->ImageMap);
+    return $this->ImageMap;
    }
 
    /* Load and cleanup the image map from disk */
@@ -3544,7 +3544,7 @@
       }
      else
       {
-       fwrite($Handle, $this->getImageMap());
+       fwrite($Handle, serialize($this->getImageMap()));
       }
      fclose ($Handle);
     }
diff --git a/libraries/chart/pma_pchart_chart.php b/libraries/chart/pma_pchart_chart.php
index 97af13604..bcca2ac28 100644
--- a/libraries/chart/pma_pchart_chart.php
+++ b/libraries/chart/pma_pchart_chart.php
@@ -171,37 +171,42 @@ abstract class PMA_pChart_Chart extends PMA_Chart
 
     public function toString()
     {
-        if (function_exists('gd_info')) {
-            $this->init();
-            $this->prepareDataSet();
-            $this->prepareChart();
-
-            //$this->chart->debugImageMap();
-
-            if ($this->isContinuous()) {
-                $this->render(1);
-            }
-            else {
-                $this->render(20);
-            }
-
-            $returnData = '<div id="chart">';
-            foreach ($this->partsEncoded as $part) {
-                $returnData .= '<img src="data:image/png;base64,'.$part.'" />';
-            }
-            $returnData .= '</div>';
-            $returnData .= '
-                <script type="text/javascript">
-                imageMap.loadImageMap(\''.$this->getImageMap().'\');
-                </script>
-            ';
-
-            return $returnData;
-        }
-        else {
+        if (!function_exists('gd_info')) {
             array_push($this->errors, ERR_NO_GD);
             return '';
         }
+
+        $this->init();
+        $this->prepareDataSet();
+        $this->prepareChart();
+
+        //$this->chart->debugImageMap();
+
+        if ($this->isContinuous()) {
+            $this->render(1);
+        }
+        else {
+            $this->render(20);
+        }
+
+        $returnData = '<div id="chart">';
+        foreach ($this->partsEncoded as $part) {
+            $returnData .= '<img src="data:image/png;base64,'.$part.'" />';
+        }
+        $returnData .= '</div>';
+
+        if (function_exists('json_encode')) {
+            $returnData .= '
+                <script type="text/javascript">
+                imageMap.loadImageMap(\''.json_encode($this->getImageMap()).'\');
+                </script>
+            ';
+        }
+        else {
+            array_push($this->errors, ERR_NO_JSON);
+        }
+
+        return $returnData;
     }
 
     protected function getLabelHeight()
diff --git a/tbl_chart.php b/tbl_chart.php
index 31118bd8c..4e8f555e2 100644
--- a/tbl_chart.php
+++ b/tbl_chart.php
@@ -50,11 +50,10 @@ if (PMA_isValid($_REQUEST['chartSettings'], 'array')) {
     $chartSettings = $_REQUEST['chartSettings'];
 }
 
-// get the chart and settings and errors after chart generation
-$chartErrors = array();
-$chart = PMA_chart_results($data, $chartSettings, $chartErrors);
+// get the chart and settings after chart generation
+$chart = PMA_chart_results($data, $chartSettings);
 
-if (empty($chartErrors)) {
+if (!empty($chart)) {
     $message = PMA_Message::success(__('Chart generated successfully.'));
 }
 else {