diff -r 0e3910f1de64 tools/python/xen/lowlevel/xc/xc.c
--- a/tools/python/xen/lowlevel/xc/xc.c	Tue Jan 12 07:17:40 2010 +0000
+++ b/tools/python/xen/lowlevel/xc/xc.c	Tue Jan 12 17:28:55 2010 +0100
@@ -1129,20 +1129,23 @@
             Py_DECREF(pyint);
             node_exists = 1;
         }
-        PyList_Append(node_to_cpu_obj, cpus); 
+        if (node_exists)
+            PyList_Append(node_to_cpu_obj, cpus); 
         Py_DECREF(cpus);
 
         /* Memory. */
         xc_availheap(self->xc_handle, 0, 0, i, &free_heap);
         node_exists = node_exists || (free_heap != 0);
         pyint = PyInt_FromLong(free_heap / 1024);
-        PyList_Append(node_to_memory_obj, pyint);
+        if (node_exists)
+            PyList_Append(node_to_memory_obj, pyint);
         Py_DECREF(pyint);
 
         /* DMA memory. */
         xc_availheap(self->xc_handle, 0, 32, i, &free_heap);
         pyint = PyInt_FromLong(free_heap / 1024);
-        PyList_Append(node_to_dma32_mem_obj, pyint);
+        if (node_exists)
+            PyList_Append(node_to_dma32_mem_obj, pyint);
         Py_DECREF(pyint);
 
         if ( node_exists )