diff --git a/ocpp-1-6-api-adapter/src/main/kotlin/com/izivia/ocpp/adapter16/mapper/CommonMapper.kt b/ocpp-1-6-api-adapter/src/main/kotlin/com/izivia/ocpp/adapter16/mapper/CommonMapper.kt
index 03cefc1a..97b7b146 100644
--- a/ocpp-1-6-api-adapter/src/main/kotlin/com/izivia/ocpp/adapter16/mapper/CommonMapper.kt
+++ b/ocpp-1-6-api-adapter/src/main/kotlin/com/izivia/ocpp/adapter16/mapper/CommonMapper.kt
@@ -128,7 +128,7 @@ abstract class CommonMapper {
     @Named("convertEVSEType")
     fun convertEVSEType(evse: EVSEType?): Int =
         if (evse != null) {
-            evse.connectorId!!
+            evse.connectorId ?: evse.id
         } else {
             throw IllegalArgumentException("Argument evse is required in OCPP 1.6 to start a transaction")
         }