diff --git a/system/helpers/captcha_helper.php b/system/helpers/captcha_helper.php
index 74ab24f..36a5374 100644
--- a/system/helpers/captcha_helper.php
+++ b/system/helpers/captcha_helper.php
@@ -216,8 +216,22 @@
 		//  Generate the image
 		// -----------------------------------
 		$img_url = rtrim($img_url, '/').'/';
-		$img_filename = $now.'.jpg';
-		ImageJPEG($im, $img_path.$img_filename);
+
+		if (function_exists('ImageJPEG'))
+		{
+			$img_filename = $now.'.jpg';
+			ImageJPEG($im, $img_path.$img_filename);
+		}
+		elseif (function_exists('ImagePNG'))
+		{
+			$img_filename = $now.'.png';
+			ImagePNG($im, $img_path.$img_filename);
+		}
+		else
+		{
+			return FALSE;
+		}
+
 		$img = '<img src="'.$img_url.$img_filename.'" style="width: '.$img_width.'; height: '.$img_height .'; border: 0;" alt=" " />';
 		ImageDestroy($im);
 
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 3215ae2..c37215d 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -137,6 +137,7 @@
       - Added *word_length* and *pool* options to allow customization of the generated word.
       - Added *colors* configuration to allow customization for the *background*, *border*, *text* and *grid* colors.
       - Added *filename* to the returned array elements.
+      - Using ImagePNG function, if ImageJPEG not exists.
 
    -  :doc:`Text Helper <helpers/text_helper>` changes include: