--- xm_internal.c.org   2009-04-07 21:50:17.000000000 +0900
+++ xm_internal.c       2009-04-13 20:53:22.000000000 +0900
@@ -1700,7 +1700,8 @@ int xenXMDomainPinVcpu(virDomainPtr doma
     ret = 0;

  cleanup:
-    VIR_FREE(mapstr);
+    if( *mapstr != '\0' )
+        VIR_FREE(mapstr);
     VIR_FREE(cpuset);
     xenUnifiedUnlock(priv);
     return (ret);
