Index: src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeRegistry.java
===================================================================
--- src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeRegistry.java	(revision 418787)
+++ src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeRegistry.java	(working copy)
@@ -1307,6 +1307,12 @@
 
         // validate supertypes
         QName[] supertypes = ntd.getSupertypes();
+        if ((supertypes == null || supertypes.length == 0)
+                && !ntd.isMixin() && !QName.NT_BASE.equals(ntd.getName())) {
+            log.info("Using nt:base as the default supertype: {}", ntd.getName());
+            ntd.setSupertypes(new QName[] { QName.NT_BASE });
+            supertypes = ntd.getSupertypes();
+        }
         if (supertypes != null && supertypes.length > 0) {
             for (int i = 0; i < supertypes.length; i++) {
                 checkNamespace(supertypes[i], nsReg);
@@ -1368,14 +1374,6 @@
                 log.debug(msg);
                 throw new InvalidNodeTypeDefException(msg, nsnte);
             }
-        } else {
-            // no supertypes specified: has to be either a mixin type or nt:base
-            if (!ntd.isMixin() && !QName.NT_BASE.equals(ntd.getName())) {
-                String msg = "[" + name
-                        + "] all primary node types except nt:base itself must be (directly or indirectly) derived from nt:base";
-                log.debug(msg);
-                throw new InvalidNodeTypeDefException(msg);
-            }
         }
 
         checkNamespace(ntd.getPrimaryItemName(), nsReg);