diff --git a/lib/api/GwApi.h b/lib/api/GwApi.h
index 9611707..b6be1cc 100644
--- a/lib/api/GwApi.h
+++ b/lib/api/GwApi.h
@@ -15,6 +15,7 @@ class GwApi{
             public:
                 double value=0;
                 bool valid=false;
+                int source=-1;
                 bool changed=false; //will be set by getBoatDataValues
                 BoatValue(){}
                 BoatValue(const String &n):name(n){
diff --git a/src/main.cpp b/src/main.cpp
index 582372e..1c6b3d3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -286,6 +286,11 @@ public:
           double newValue=item->getDoubleValue();
           if (newValue != list[i]->value) list[i]->changed=true;
           list[i]->value=newValue;
+          int newSource=item->getLastSource();
+          if (newSource != list[i]->source){
+            list[i]->source=newSource;
+            list[i]->changed=true;
+          }
         }
         list[i]->setFormat(item->getFormat());
       }