diff --git a/hsarback/src/de/hsadmin/mods/dom/DomainProcessorFactory.java b/hsarback/src/de/hsadmin/mods/dom/DomainProcessorFactory.java
index 8242798..6c915ed 100644
--- a/hsarback/src/de/hsadmin/mods/dom/DomainProcessorFactory.java
+++ b/hsarback/src/de/hsadmin/mods/dom/DomainProcessorFactory.java
@@ -423,7 +423,12 @@ public class DomainProcessorFactory implements EntityProcessorFactory {
 				}
 				final String validSubdomains = d.getValidsubdomainnames();
 				if (autoconfig && !validSubdomains.contains("autoconfig")) {
-					d.setValidsubdomainnames(validSubdomains + ",autoconfig");
+					if (validSubdomains.length() > 0) {
+						d.setValidsubdomainnames(validSubdomains + ",autoconfig");
+					}
+					else {
+						d.setValidsubdomainnames("autoconfig");
+					}
 				}
 			}
 		}