diff --git a/plugin.py b/plugin.py
index 26a15f6..1d75212 100644
--- a/plugin.py
+++ b/plugin.py
@@ -9,7 +9,7 @@
 #
 
 """
-<plugin key="SolarEdge_ModbusTCP" name="SolarEdge ModbusTCP" author="Addie Janssen" version="1.0.3" externallink="https://github.com/addiejanssen/domoticz-solaredge-modbustcp-plugin">
+<plugin key="SolarEdge_ModbusTCP" name="SolarEdge ModbusTCP" author="Addie Janssen" version="1.0.4" externallink="https://github.com/addiejanssen/domoticz-solaredge-modbustcp-plugin">
     <params>
         <param field="Address" label="Inverter IP Address" width="150px" required="true" />
         <param field="Port" label="Inverter Port Number" width="100px" required="true" default="502" />
@@ -334,7 +334,7 @@ class BasePlugin:
                                 lookup_table = unit[Column.LOOKUP]
                                 to_lookup = int(inverter_values[unit[Column.MODBUSNAME]])
 
-                                if to_lookup < len(lookup_table):
+                                if to_lookup >= 0 and to_lookup < len(lookup_table):
                                     value = lookup_table[to_lookup]
                                 else:
                                     value = "Key not found in lookup table: {}".format(to_lookup)