diff --git a/admin_manual/configuration_server/config_sample_php_parameters.rst b/admin_manual/configuration_server/config_sample_php_parameters.rst
index 48ba7c182..85536e4e6 100644
--- a/admin_manual/configuration_server/config_sample_php_parameters.rst
+++ b/admin_manual/configuration_server/config_sample_php_parameters.rst
@@ -1246,9 +1246,11 @@ Defaults to ``4096``
 
 	'preview_max_filesize_image' => 50,
 
-max file size for generating image previews with imagegd (default behavior)
+Max file size for generating image previews with imagegd (default behavior).
+
 If the image is bigger, it'll try other preview generators, but will most
-likely show the default mimetype icon. Set to -1 for no limit.
+likely either show the default mimetype icon or not display the image at all.
+Set to ``-1`` for no limit and try to generate image previews on all file sizes.
 
 Defaults to ``50`` megabytes