diff --git a/man/man5/monitorix.conf.5 b/man/man5/monitorix.conf.5
index 7ad9359..833817d 100644
--- a/man/man5/monitorix.conf.5
+++ b/man/man5/monitorix.conf.5
@@ -145,6 +145,14 @@ In order to mitigate this situation this option sets the priority in which Monit
 Default value: \fI0\fP
 .RE
 .P
+.BI image_format
+.RS
+This is the format of each generated graph. There are only two possible values: 
+\fIPNG\fP and \fISVG\fP.
+.P
+Default value: \fIPNG\fP
+.RE
+.P
 .BI include_dir
 .RS
 The main configuration file is usually called \fImonitorix.conf\fP and its location is provided as part of the command line arguments. In addition, other configuration files may be loaded placing them in the directory pointed by this option. The names must end with .conf to be included.