diff --git a/libraries/gis/pma_gis_visualization.php b/libraries/gis/pma_gis_visualization.php
index 7c368570b2..7405bd23b4 100644
--- a/libraries/gis/pma_gis_visualization.php
+++ b/libraries/gis/pma_gis_visualization.php
@@ -74,6 +74,8 @@ class PMA_GIS_Visualization
 
     /**
      * All the variable initialization, options handling has to be done here.
+     *
+     * @return nothing
      */
     protected function init()
     {
@@ -83,6 +85,8 @@ class PMA_GIS_Visualization
     /**
      * A function which handles passed parameters. Useful if desired
      * chart needs to be a little bit different from the default one.
+     *
+     * @return nothing
      */
     private function _handleOptions()
     {
@@ -121,6 +125,8 @@ class PMA_GIS_Visualization
      * @param string $file_name file name
      * @param string $type      mime type
      * @param string $ext       extension of the file
+     *
+     * @return nothing
      */
     private function _toFile($file_name, $type, $ext)
     {
@@ -179,6 +185,8 @@ class PMA_GIS_Visualization
      * Saves as a SVG image to a file.
      *
      * @param string $file_name File name
+     *
+     * @return nothing
      */
     public function toFileAsSvg($file_name)
     {
@@ -234,6 +242,8 @@ class PMA_GIS_Visualization
      * Saves as a PNG image to a file.
      *
      * @param string $file_name File name
+     *
+     * @return nothing
      */
     public function toFileAsPng($file_name)
     {
@@ -260,6 +270,8 @@ class PMA_GIS_Visualization
      * Saves as a PDF to a file.
      *
      * @param string $file_name File name
+     *
+     * @return nothing
      */
     public function toFileAsPdf($file_name)
     {