diff --git a/datastore_server/source/java/ch/systemsx/cisd/etlserver/ThreadParameters.java b/datastore_server/source/java/ch/systemsx/cisd/etlserver/ThreadParameters.java
index 96094c995dc5c44ab99f3938cbd424ad175e5d88..b9aa9c08b14bc02f3df0115443eaf2c3af7b6634 100644
--- a/datastore_server/source/java/ch/systemsx/cisd/etlserver/ThreadParameters.java
+++ b/datastore_server/source/java/ch/systemsx/cisd/etlserver/ThreadParameters.java
@@ -295,7 +295,7 @@ public final class ThreadParameters
     {
         if (createIncomingDirectories && incomingDataDirectory.exists() == false)
         {
-            incomingDataDirectory.mkdir();
+            incomingDataDirectory.mkdirs();
             operationLog.info("Created incoming directory '" + incomingDataDirectory + "'.");
         }
         if (incomingDataDirectory.isDirectory() == false)