diff --git a/Report/DefaultReports/JahresReport.cs b/Report/DefaultReports/JahresReport.cs
index 95bb89f3b..2afd46c04 100644
--- a/Report/DefaultReports/JahresReport.cs
+++ b/Report/DefaultReports/JahresReport.cs
@@ -47,14 +47,16 @@ namespace BeWo.Report.DefaultReports
                     var allCustomerNames = new List<String>();
                     foreach (var item in tab.JahresReportDetailList)
                     {
-                        foreach (var name in item.CustomerNames)
+                        if (item.CustomerNames != null)
                         {
-                            if (!allCustomerNames.Contains(name))
+                            foreach (var name in item.CustomerNames)
                             {
-                                allCustomerNames.Add(name);
+                                if (!allCustomerNames.Contains(name))
+                                {
+                                    allCustomerNames.Add(name);
+                                }
                             }
                         }
-                        
                     }
                     var sorted = allCustomerNames.OrderBy(a => a).ToList();