diff --git a/pandora_server/ChangeLog b/pandora_server/ChangeLog
index fd0a7508aa..563dce0233 100644
--- a/pandora_server/ChangeLog
+++ b/pandora_server/ChangeLog
@@ -1,3 +1,8 @@
+2011-08-18  Ramon Novoa  <rnovoa@artica.es>
+
+	* lib/PandoraFMS/NetworkServer.pm,
+	  lib/PandoraFMS/Core.pm: Fixed some warnings on undefined values.
+
 2011-08-17  Sancho Lerena <slerena@artica.es>
 
 	* SNMPServer.pm: Custom value and custom type are not used anymore.
diff --git a/pandora_server/lib/PandoraFMS/Core.pm b/pandora_server/lib/PandoraFMS/Core.pm
index a8bde6d78e..6afadb6460 100644
--- a/pandora_server/lib/PandoraFMS/Core.pm
+++ b/pandora_server/lib/PandoraFMS/Core.pm
@@ -166,7 +166,7 @@ our @EXPORT = qw(
 	pandora_server_statistics
 	pandora_self_monitoring
 	pandora_process_policy_queue
-    get_agent_from_addr
+	get_agent_from_addr
 	@ServerTypes
 	);
 
@@ -2433,8 +2433,11 @@ sub pandora_self_monitoring ($$) {
 	$xml_output .=" </module>";
 
 	my $load_average = load_average();
-	my $free_mem = free_mem();;
+	$load_average = '' unless defined ($load_average);
+	my $free_mem = free_mem();
+	$free_mem = '' unless defined ($load_average);
 	my $free_disk_spool = disk_free ($pa_config->{"incomingdir"});
+	$free_disk_spool = '' unless defined ($free_disk_spool);
 	my $my_data_server = get_db_value ($dbh, "SELECT id_server FROM tserver WHERE server_type = 0 AND name = '".$pa_config->{"servername"}."'");
 
 	# Number of unknown agents
diff --git a/pandora_server/lib/PandoraFMS/NetworkServer.pm b/pandora_server/lib/PandoraFMS/NetworkServer.pm
index bcf5b67b09..1976143c48 100644
--- a/pandora_server/lib/PandoraFMS/NetworkServer.pm
+++ b/pandora_server/lib/PandoraFMS/NetworkServer.pm
@@ -329,9 +329,8 @@ sub pandora_query_snmp ($$$) {
 	# SNMP v1, v2 and v2c call
 	if ($snmp_version ne '3'){
 
-        $output = pandora_snmp_get_command ($snmpget_cmd, $snmp_version, $snmp_retries, $snmp_timeout, $snmp_community, $snmp_target, $snmp_oid, "", "");
-
-		if ($output ne ""){
+		$output = pandora_snmp_get_command ($snmpget_cmd, $snmp_version, $snmp_retries, $snmp_timeout, $snmp_community, $snmp_target, $snmp_oid, "", "");
+		if (defined ($output) && $output ne ""){
 			$module_result = 0;
 			$module_data = $output;
 		}
@@ -352,10 +351,9 @@ sub pandora_query_snmp ($$$) {
 			$snmp3_extra = " -a $snmp3_auth_method -u $snmp3_auth_user -A $snmp3_auth_pass -x $snmp3_privacy_method -X $snmp3_privacy_pass ";
 		}
        
-        $snmp3_execution = pandora_snmp_get_command ($snmpget_cmd, $snmp_version, $snmp_retries, $snmp_timeout, $snmp_community, $snmp_target, $snmp_oid, $snmp3_security_level, $snmp3_extra);
-
+		$snmp3_execution = pandora_snmp_get_command ($snmpget_cmd, $snmp_version, $snmp_retries, $snmp_timeout, $snmp_community, $snmp_target, $snmp_oid, $snmp3_security_level, $snmp3_extra);
 		$output = `$snmp3_execution`;
-		if ($output ne ""){
+		if (defined ($output) && $output ne ""){
 			$module_result = 0;
 			$module_data = $output;
 		}