diff --git a/addon/www/rest.cgi b/addon/www/rest.cgi
index 5ae1ba5..fb71410 100644
--- a/addon/www/rest.cgi
+++ b/addon/www/rest.cgi
@@ -54,8 +54,8 @@ proc process {} {
 			return [rmupdate::get_firmware_info]
 		} elseif {[lindex $path 1] == "get_system_info"} {
 			set system_type [rmupdate::get_rpi_version]
-			set root_partition [rmupdate::get_current_root_partition_number]
-			return "\{\"system_type\":\"${system_type}\",\"root_partition\":${root_partition}\}"
+			set root_partition [rmupdate::get_partition_device [rmupdate::get_system_device] [rmupdate::get_current_root_partition_number]]
+			return "\{\"system_type\":\"${system_type}\",\"root_partition\":\"${root_partition}\"\}"
 		} elseif {[lindex $path 1] == "system_reboot"} {
 			exec /sbin/reboot
 			return "\"reboot initiated\""