diff --git a/pandora_console/operation/agentes/networkmap.groups.php b/pandora_console/operation/agentes/networkmap.groups.php
index ceaabb1a7c..a60b0e3b11 100644
--- a/pandora_console/operation/agentes/networkmap.groups.php
+++ b/pandora_console/operation/agentes/networkmap.groups.php
@@ -60,6 +60,9 @@ $strict_user = db_get_value('strict_acl', 'tusuario', 'id_user', $config['id_use
 // Set filter
 $filter = networkmap_get_filter ($layout);
 
+if (!isset($size_canvas)) {
+	$size_canvas = null;
+}
 
 // Generate dot file
 $graph = networkmap_generate_dot_groups (__('Pandora FMS'), $group,
diff --git a/pandora_console/operation/agentes/networkmap.topology.php b/pandora_console/operation/agentes/networkmap.topology.php
index 5493cdd073..54e5272a1b 100644
--- a/pandora_console/operation/agentes/networkmap.topology.php
+++ b/pandora_console/operation/agentes/networkmap.topology.php
@@ -64,6 +64,9 @@ if (!isset($text_filter)) {
 	$text_filter = '';
 }
 
+if (!isset($size_canvas)) {
+	$size_canvas = null;
+}
 
 
 // Generate dot file