diff --git a/src/smq/snmp/snmp.go b/src/smq/snmp/snmp.go
index fea7821..e882687 100644
--- a/src/smq/snmp/snmp.go
+++ b/src/smq/snmp/snmp.go
@@ -114,7 +114,7 @@ func Start() {
                 convertedValue = fmt.Sprintf("%d", gosnmp.ToBigInt(variable.Value))
               }
 
-              diffValue := "0"
+              diffValue := "-"
               if oidTopic.Diff == "true" {
                 log.Println("Calculate difference to last value")
                 key := endpoint.Endpoint + ":" + oidTopic.OID