diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 39373385fc..54cdd413c8 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2100,6 +2100,8 @@ void init_build_info(libxl_domain_build_info *b_info, libxl_domain_create_info *
         b_info->u.hvm.acpi = 1;
         b_info->u.hvm.nx = 1;
         b_info->u.hvm.viridian = 0;
+    } else {
+        b_info->u.pv.slack_memkb = 8 * 1024;
     }
 }
 
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 2ac3669afa..900f020c13 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -80,6 +80,7 @@ typedef struct {
             char *timeoffset;
         } hvm;
         struct {
+            uint32_t   slack_memkb;
             const char *cmdline;
             const char *ramdisk;
             const char *features;
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index aeb96d4e3c..f99f20e976 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -53,7 +53,9 @@ int build_pre(struct libxl_ctx *ctx, uint32_t domid,
         xc_set_hvm_param(ctx->xch, domid, HVM_PARAM_VPT_ALIGN, (unsigned long) info->vpt_align);
     xc_domain_max_vcpus(ctx->xch, domid, info->max_vcpus);
     xc_domain_setmaxmem(ctx->xch, domid, info->max_memkb + info->video_memkb);
-    xc_domain_set_memmap_limit(ctx->xch, domid, info->max_memkb);
+    xc_domain_set_memmap_limit(ctx->xch, domid, 
+            (info->hvm) ? info->max_memkb : 
+            (info->max_memkb + info->u.pv.slack_memkb));
 
     if (info->hvm) {
         unsigned long shadow;