diff --git a/src/ag-chart.c b/src/ag-chart.c
index 68caae2..5e9a7c4 100644
--- a/src/ag-chart.c
+++ b/src/ag-chart.c
@@ -187,6 +187,11 @@ ag_chart_set_property(GObject      *gobject,
         case PROP_NOTE:
             ag_chart_set_note(AG_CHART(gobject), g_value_get_string(value));
 
+            break;
+
+        default:
+            G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, param_spec);
+
             break;
     }
 }
@@ -218,6 +223,11 @@ ag_chart_get_property(GObject    *gobject,
         case PROP_NOTE:
             g_value_set_string(value, priv->note);
 
+            break;
+
+        default:
+            G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, param_spec);
+
             break;
     }
 }