diff -rup libvirt-0.6.2.orig/src/xm_internal.c libvirt-0.6.2.new/src/xm_internal.c
--- libvirt-0.6.2.orig/src/xm_internal.c	2009-04-03 15:04:28.000000000 +0100
+++ libvirt-0.6.2.new/src/xm_internal.c	2009-04-23 10:53:10.000000000 +0100
@@ -2912,7 +2912,8 @@ xenXMDomainDetachDevice(virDomainPtr dom
                 if (i < (def->ndisks - 1))
                     memmove(def->disks + i,
                             def->disks + i + 1,
-                            def->ndisks - (i + 1));
+                            sizeof(*def->disks) *
+                            (def->ndisks - (i + 1)));
                 break;
             }
         }
@@ -2929,7 +2930,8 @@ xenXMDomainDetachDevice(virDomainPtr dom
                 if (i < (def->nnets - 1))
                     memmove(def->nets + i,
                             def->nets + i + 1,
-                            def->nnets - (i + 1));
+                            sizeof(*def->nets) *
+                            (def->nnets - (i + 1)));
                 break;
             }
         }