diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 150d7271d6..a9e4dc1540 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1477,7 +1477,37 @@ int xc_tbuf_set_evt_mask(xc_interface *xch, uint32_t mask);
 int xc_domctl(xc_interface *xch, struct xen_domctl *domctl);
 int xc_sysctl(xc_interface *xch, struct xen_sysctl *sysctl);
 
-int xc_version(xc_interface *xch, int cmd, void *arg);
+/**
+ * This function returns the size of buffer to be allocated for
+ * the cmd. The cmd are XEN_VERSION_*.
+ */
+ssize_t xc_version_len(xc_interface *xch, unsigned int cmd);
+
+/**
+ * This function retrieves the information from the version_op hypercall.
+ * The len is the size of the arg buffer. If arg is NULL, will not
+ * perform hypercall - instead will just return the size of arg
+ * buffer that is needed.
+ *
+ * Note that prior to Xen 4.7 this would return 0 for success and
+ * negative value (-1) for error (with the error in errno). In Xen 4.7
+ * and later for success it will return an positive value which is the
+ * number of bytes copied in arg.
+ *
+ * It can also return -1 with various errno values:
+ *  - EPERM - not permitted.
+ *  - ENOBUFS - the len was to short, output in arg truncated.
+ *  - ENOSYS - not implemented.
+ *
+ * @parm xch a handle to an open hypervisor interface
+ * @parm cmd XEN_VERSION_* value
+ * @param arg Pointer to xen_version_op_buf_t or xen_version_op_val_t
+ * @param len Size of arg
+ * @return size of bytes copied in arg on success, -1 on failure (and
+ * errno will contain the error)
+ *
+ */
+int xc_version(xc_interface *xch, unsigned int cmd, void *arg, size_t len);
 
 int xc_flask_op(xc_interface *xch, xen_flask_op_t *op);
 
diff --git a/tools/libxc/xc_core.c b/tools/libxc/xc_core.c
index d792566a99..cfeba6b7bd 100644
--- a/tools/libxc/xc_core.c
+++ b/tools/libxc/xc_core.c
@@ -270,42 +270,43 @@ elfnote_fill_xen_version(xc_interface *xch,
                          *xen_version)
 {
     int rc;
+    xen_version_op_val_t val = 0;
     memset(xen_version, 0, sizeof(*xen_version));
 
-    rc = xc_version(xch, XENVER_version, NULL);
+    rc = xc_version(xch, XEN_VERSION_version, &val, sizeof(val));
     if ( rc < 0 )
         return rc;
-    xen_version->major_version = rc >> 16;
-    xen_version->minor_version = rc & ((1 << 16) - 1);
+    xen_version->major_version = val >> 16;
+    xen_version->minor_version = val & ((1 << 16) - 1);
 
-    rc = xc_version(xch, XENVER_extraversion,
-                    &xen_version->extra_version);
+    rc = xc_version(xch, XEN_VERSION_extraversion,
+                    xen_version->extra_version,
+                    sizeof(xen_version->extra_version));
     if ( rc < 0 )
         return rc;
 
-    rc = xc_version(xch, XENVER_compile_info,
-                    &xen_version->compile_info);
+    rc = xc_version(xch, XEN_VERSION_capabilities,
+                    xen_version->capabilities,
+                    sizeof(xen_version->capabilities));
     if ( rc < 0 )
         return rc;
 
-    rc = xc_version(xch,
-                    XENVER_capabilities, &xen_version->capabilities);
+    rc = xc_version(xch, XEN_VERSION_changeset, xen_version->changeset,
+                    sizeof(xen_version->changeset));
     if ( rc < 0 )
         return rc;
 
-    rc = xc_version(xch, XENVER_changeset, &xen_version->changeset);
+    rc = xc_version(xch, XEN_VERSION_platform_parameters,
+                    &xen_version->platform_parameters,
+                    sizeof(xen_version->platform_parameters));
     if ( rc < 0 )
         return rc;
 
-    rc = xc_version(xch, XENVER_platform_parameters,
-                    &xen_version->platform_parameters);
+    val = 0;
+    rc = xc_version(xch, XEN_VERSION_pagesize, &val, sizeof(val));
     if ( rc < 0 )
         return rc;
-
-    rc = xc_version(xch, XENVER_pagesize, NULL);
-    if ( rc < 0 )
-        return rc;
-    xen_version->pagesize = rc;
+    xen_version->pagesize = val;
 
     return 0;
 }
diff --git a/tools/libxc/xc_dom_boot.c b/tools/libxc/xc_dom_boot.c
index 791041b322..bbff72e429 100644
--- a/tools/libxc/xc_dom_boot.c
+++ b/tools/libxc/xc_dom_boot.c
@@ -112,11 +112,19 @@ int xc_dom_compat_check(struct xc_dom_image *dom)
 
 int xc_dom_boot_xen_init(struct xc_dom_image *dom, xc_interface *xch, domid_t domid)
 {
+    xen_version_op_val_t val = 0;
+
+    if ( xc_version(xch, XEN_VERSION_version, &val, sizeof(val)) < 0 )
+    {
+        xc_dom_panic(xch, XC_INTERNAL_ERROR, "can't get Xen version!");
+        return -1;
+    }
+    dom->xen_version = val;
     dom->xch = xch;
     dom->guest_domid = domid;
 
-    dom->xen_version = xc_version(xch, XENVER_version, NULL);
-    if ( xc_version(xch, XENVER_capabilities, &dom->xen_caps) < 0 )
+    if ( xc_version(xch, XEN_VERSION_capabilities, dom->xen_caps,
+                    sizeof(dom->xen_caps)) < 0 )
     {
         xc_dom_panic(xch, XC_INTERNAL_ERROR, "can't get xen capabilities");
         return -1;
diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index 050216e028..9ebd1d67d3 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -2084,7 +2084,8 @@ int xc_map_domain_meminfo(xc_interface *xch, int domid,
     _di.guest_width = minfo->guest_width;
 
     /* Get page table levels (see get_platform_info() in xg_save_restore.h */
-    if ( xc_version(xch, XENVER_capabilities, &xen_caps) )
+    if ( xc_version(xch, XEN_VERSION_capabilities, xen_caps,
+                    sizeof(xen_caps)) < 0 )
     {
         PERROR("Could not get Xen capabilities (for page table levels)");
         return -1;
diff --git a/tools/libxc/xc_private.c b/tools/libxc/xc_private.c
index c41e43351f..631ad91fb5 100644
--- a/tools/libxc/xc_private.c
+++ b/tools/libxc/xc_private.c
@@ -457,58 +457,23 @@ int xc_sysctl(xc_interface *xch, struct xen_sysctl *sysctl)
     return do_sysctl(xch, sysctl);
 }
 
-int xc_version(xc_interface *xch, int cmd, void *arg)
+ssize_t xc_version_len(xc_interface *xch, unsigned int cmd)
 {
-    DECLARE_HYPERCALL_BOUNCE(arg, 0, XC_HYPERCALL_BUFFER_BOUNCE_OUT); /* Size unknown until cmd decoded */
-    size_t sz;
+    return do_version_op(xch, cmd, NULL, 0);
+}
+
+int xc_version(xc_interface *xch, unsigned int cmd, void *arg, size_t sz)
+{
+    DECLARE_HYPERCALL_BOUNCE(arg, sz, XC_HYPERCALL_BUFFER_BOUNCE_OUT);
     int rc;
 
-    switch ( cmd )
-    {
-    case XENVER_version:
-        sz = 0;
-        break;
-    case XENVER_extraversion:
-        sz = sizeof(xen_extraversion_t);
-        break;
-    case XENVER_compile_info:
-        sz = sizeof(xen_compile_info_t);
-        break;
-    case XENVER_capabilities:
-        sz = sizeof(xen_capabilities_info_t);
-        break;
-    case XENVER_changeset:
-        sz = sizeof(xen_changeset_info_t);
-        break;
-    case XENVER_platform_parameters:
-        sz = sizeof(xen_platform_parameters_t);
-        break;
-    case XENVER_get_features:
-        sz = sizeof(xen_feature_info_t);
-        break;
-    case XENVER_pagesize:
-        sz = 0;
-        break;
-    case XENVER_guest_handle:
-        sz = sizeof(xen_domain_handle_t);
-        break;
-    case XENVER_commandline:
-        sz = sizeof(xen_commandline_t);
-        break;
-    default:
-        ERROR("xc_version: unknown command %d\n", cmd);
-        return -EINVAL;
-    }
-
-    HYPERCALL_BOUNCE_SET_SIZE(arg, sz);
-
-    if ( (sz != 0) && xc_hypercall_bounce_pre(xch, arg) )
+    if ( xc_hypercall_bounce_pre(xch, arg) )
     {
         PERROR("Could not bounce buffer for version hypercall");
         return -ENOMEM;
     }
 
-    rc = do_xen_version(xch, cmd, HYPERCALL_BUFFER(arg));
+    rc = do_version_op(xch, cmd, HYPERCALL_BUFFER(arg), sz);
 
     if ( sz != 0 )
         xc_hypercall_bounce_post(xch, arg);
diff --git a/tools/libxc/xc_private.h b/tools/libxc/xc_private.h
index aa8daf1b1c..5be8fdd64f 100644
--- a/tools/libxc/xc_private.h
+++ b/tools/libxc/xc_private.h
@@ -214,11 +214,12 @@ void xc__hypercall_buffer_cache_release(xc_interface *xch);
  * Hypercall interfaces.
  */
 
-static inline int do_xen_version(xc_interface *xch, int cmd, xc_hypercall_buffer_t *dest)
+static inline long do_version_op(xc_interface *xch, int cmd,
+                                 xc_hypercall_buffer_t *dest, ssize_t len)
 {
     DECLARE_HYPERCALL_BUFFER_ARGUMENT(dest);
-    return xencall2(xch->xcall, __HYPERVISOR_xen_version,
-                    cmd, HYPERCALL_BUFFER_AS_ARG(dest));
+    return xencall3(xch->xcall, __HYPERVISOR_version_op,
+                    cmd, HYPERCALL_BUFFER_AS_ARG(dest), len);
 }
 
 static inline int do_physdev_op(xc_interface *xch, int cmd, void *op, size_t len)
diff --git a/tools/libxc/xc_resume.c b/tools/libxc/xc_resume.c
index e692b810f7..5bf4cf0f73 100644
--- a/tools/libxc/xc_resume.c
+++ b/tools/libxc/xc_resume.c
@@ -56,7 +56,8 @@ static int modify_returncode(xc_interface *xch, uint32_t domid)
             return 0;
 
         /* HVM guests have host address width. */
-        if ( xc_version(xch, XENVER_capabilities, &caps) != 0 )
+        if ( xc_version(xch, XEN_VERSION_capabilities, caps,
+                        sizeof(caps)) < 0 )
         {
             PERROR("Could not get Xen capabilities");
             return -1;
diff --git a/tools/libxc/xc_sr_save.c b/tools/libxc/xc_sr_save.c
index 388ae7fd3a..7f1818caf9 100644
--- a/tools/libxc/xc_sr_save.c
+++ b/tools/libxc/xc_sr_save.c
@@ -9,7 +9,7 @@
 static int write_headers(struct xc_sr_context *ctx, uint16_t guest_type)
 {
     xc_interface *xch = ctx->xch;
-    int32_t xen_version = xc_version(xch, XENVER_version, NULL);
+    xen_version_op_val_t xen_version;
     struct xc_sr_ihdr ihdr =
         {
             .marker  = IHDR_MARKER,
@@ -21,15 +21,16 @@ static int write_headers(struct xc_sr_context *ctx, uint16_t guest_type)
         {
             .type       = guest_type,
             .page_shift = XC_PAGE_SHIFT,
-            .xen_major  = (xen_version >> 16) & 0xffff,
-            .xen_minor  = (xen_version)       & 0xffff,
         };
 
-    if ( xen_version < 0 )
+    if ( xc_version(xch, XEN_VERSION_version, &xen_version,
+                    sizeof(xen_version)) < 0 )
     {
         PERROR("Unable to obtain Xen Version");
         return -1;
     }
+    dhdr.xen_major = (xen_version >> 16) & 0xffff;
+    dhdr.xen_minor = (xen_version)       & 0xffff;
 
     if ( write_exact(ctx->fd, &ihdr, sizeof(ihdr)) )
     {
diff --git a/tools/libxc/xg_save_restore.h b/tools/libxc/xg_save_restore.h
index 303081df0d..007875f6f1 100644
--- a/tools/libxc/xg_save_restore.h
+++ b/tools/libxc/xg_save_restore.h
@@ -57,10 +57,12 @@ static inline int get_platform_info(xc_interface *xch, uint32_t dom,
     xen_capabilities_info_t xen_caps = "";
     xen_platform_parameters_t xen_params;
 
-    if (xc_version(xch, XENVER_platform_parameters, &xen_params) != 0)
+    if (xc_version(xch, XEN_VERSION_platform_parameters, &xen_params,
+                   sizeof(xen_params)) < 0)
         return 0;
 
-    if (xc_version(xch, XENVER_capabilities, &xen_caps) != 0)
+    if (xc_version(xch, XEN_VERSION_capabilities, xen_caps,
+                   sizeof(xen_caps)) < 0)
         return 0;
 
     if (xc_maximum_ram_page(xch, max_mfn))
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 20e0019d9c..ac4d1f673a 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -5207,50 +5207,71 @@ libxl_numainfo *libxl_get_numainfo(libxl_ctx *ctx, int *nr)
     return ret;
 }
 
+
+static int libxl__xc_version_wrapper(libxl__gc *gc, unsigned int cmd,
+                                     char *buf, ssize_t len, char **dst)
+{
+    int r;
+
+    r = xc_version(CTX->xch, cmd, buf, len);
+    if ( r == -EPERM ) {
+        buf[0] = '\0';
+    } else if ( r < 0 ) {
+        return r;
+    }
+    *dst = libxl__strdup(NOGC, buf);
+    return 0;
+}
+
 const libxl_version_info* libxl_get_version_info(libxl_ctx *ctx)
 {
     GC_INIT(ctx);
-    union {
-        xen_extraversion_t xen_extra;
-        xen_compile_info_t xen_cc;
-        xen_changeset_info_t xen_chgset;
-        xen_capabilities_info_t xen_caps;
-        xen_platform_parameters_t p_parms;
-        xen_commandline_t xen_commandline;
-    } u;
-    long xen_version;
+    char *buf;
+    xen_version_op_val_t val = 0;
     libxl_version_info *info = &ctx->version_info;
 
     if (info->xen_version_extra != NULL)
         goto out;
 
-    xen_version = xc_version(ctx->xch, XENVER_version, NULL);
-    info->xen_version_major = xen_version >> 16;
-    info->xen_version_minor = xen_version & 0xFF;
+    if (xc_version(CTX->xch, XEN_VERSION_pagesize, &val, sizeof(val)) < 0)
+        goto out;
 
-    xc_version(ctx->xch, XENVER_extraversion, &u.xen_extra);
-    info->xen_version_extra = libxl__strdup(NOGC, u.xen_extra);
+    info->pagesize = val;
+    /* 4K buffer. */
+    buf = libxl__zalloc(gc, info->pagesize);
 
-    xc_version(ctx->xch, XENVER_compile_info, &u.xen_cc);
-    info->compiler = libxl__strdup(NOGC, u.xen_cc.compiler);
-    info->compile_by = libxl__strdup(NOGC, u.xen_cc.compile_by);
-    info->compile_domain = libxl__strdup(NOGC, u.xen_cc.compile_domain);
-    info->compile_date = libxl__strdup(NOGC, u.xen_cc.compile_date);
+    val = 0;
+    if (xc_version(CTX->xch, XEN_VERSION_version, &val, sizeof(val)) < 0)
+        goto out;
+    info->xen_version_major = val >> 16;
+    info->xen_version_minor = val & 0xFF;
 
-    xc_version(ctx->xch, XENVER_capabilities, &u.xen_caps);
-    info->capabilities = libxl__strdup(NOGC, u.xen_caps);
+    if (libxl__xc_version_wrapper(gc, XEN_VERSION_extraversion, buf,
+                                  info->pagesize, &info->xen_version_extra) < 0)
+        goto out;
 
-    xc_version(ctx->xch, XENVER_changeset, &u.xen_chgset);
-    info->changeset = libxl__strdup(NOGC, u.xen_chgset);
+    info->compiler = libxl__strdup(NOGC, "");
+    info->compile_by = libxl__strdup(NOGC, "");
+    info->compile_domain = libxl__strdup(NOGC, "");
+    info->compile_date = libxl__strdup(NOGC, "");
 
-    xc_version(ctx->xch, XENVER_platform_parameters, &u.p_parms);
-    info->virt_start = u.p_parms.virt_start;
+    if (libxl__xc_version_wrapper(gc, XEN_VERSION_capabilities, buf,
+                                  info->pagesize, &info->capabilities) < 0)
+        goto out;
 
-    info->pagesize = xc_version(ctx->xch, XENVER_pagesize, NULL);
+    if (libxl__xc_version_wrapper(gc, XEN_VERSION_changeset, buf,
+                                  info->pagesize, &info->changeset) < 0)
+        goto out;
 
-    xc_version(ctx->xch, XENVER_commandline, &u.xen_commandline);
-    info->commandline = libxl__strdup(NOGC, u.xen_commandline);
+    val = 0;
+    if (xc_version(CTX->xch, XEN_VERSION_platform_parameters, &val,
+                   sizeof(val)) < 0)
+        goto out;
 
+    info->virt_start = val;
+
+    (void)libxl__xc_version_wrapper(gc, XEN_VERSION_commandline, buf,
+                                    info->pagesize, &info->commandline);
  out:
     GC_FREE;
     return info;
diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 74928e926c..4ac5dce2c4 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -853,21 +853,21 @@ CAMLprim value stub_xc_version_version(value xch)
 	CAMLparam1(xch);
 	CAMLlocal1(result);
 	xen_extraversion_t extra;
-	long packed;
+	xen_version_op_val_t packed;
 	int retval;
 
 	caml_enter_blocking_section();
-	packed = xc_version(_H(xch), XENVER_version, NULL);
+	retval = xc_version(_H(xch), XEN_VERSION_version, &packed, sizeof(packed));
 	caml_leave_blocking_section();
 
-	if (packed < 0)
+	if (retval < 0)
 		failwith_xc(_H(xch));
 
 	caml_enter_blocking_section();
-	retval = xc_version(_H(xch), XENVER_extraversion, &extra);
+	retval = xc_version(_H(xch), XEN_VERSION_extraversion, &extra, sizeof(extra));
 	caml_leave_blocking_section();
 
-	if (retval)
+	if (retval < 0)
 		failwith_xc(_H(xch));
 
 	result = caml_alloc_tuple(3);
@@ -884,37 +884,28 @@ CAMLprim value stub_xc_version_compile_info(value xch)
 {
 	CAMLparam1(xch);
 	CAMLlocal1(result);
-	xen_compile_info_t ci;
-	int retval;
-
-	caml_enter_blocking_section();
-	retval = xc_version(_H(xch), XENVER_compile_info, &ci);
-	caml_leave_blocking_section();
-
-	if (retval)
-		failwith_xc(_H(xch));
 
 	result = caml_alloc_tuple(4);
 
-	Store_field(result, 0, caml_copy_string(ci.compiler));
-	Store_field(result, 1, caml_copy_string(ci.compile_by));
-	Store_field(result, 2, caml_copy_string(ci.compile_domain));
-	Store_field(result, 3, caml_copy_string(ci.compile_date));
+	Store_field(result, 0, caml_copy_string(""));
+	Store_field(result, 1, caml_copy_string(""));
+	Store_field(result, 2, caml_copy_string(""));
+	Store_field(result, 3, caml_copy_string(""));
 
 	CAMLreturn(result);
 }
 
 
-static value xc_version_single_string(value xch, int code, void *info)
+static value xc_version_single_string(value xch, int code, void *info, ssize_t len)
 {
 	CAMLparam1(xch);
 	int retval;
 
 	caml_enter_blocking_section();
-	retval = xc_version(_H(xch), code, info);
+	retval = xc_version(_H(xch), code, info, len);
 	caml_leave_blocking_section();
 
-	if (retval)
+	if (retval < 0)
 		failwith_xc(_H(xch));
 
 	CAMLreturn(caml_copy_string((char *)info));
@@ -925,7 +916,8 @@ CAMLprim value stub_xc_version_changeset(value xch)
 {
 	xen_changeset_info_t ci;
 
-	return xc_version_single_string(xch, XENVER_changeset, &ci);
+	return xc_version_single_string(xch, XEN_VERSION_changeset,
+					&ci, sizeof(ci));
 }
 
 
@@ -933,7 +925,8 @@ CAMLprim value stub_xc_version_capabilities(value xch)
 {
 	xen_capabilities_info_t ci;
 
-	return xc_version_single_string(xch, XENVER_capabilities, &ci);
+	return xc_version_single_string(xch, XEN_VERSION_capabilities,
+					&ci, sizeof(ci));
 }
 
 
diff --git a/tools/python/xen/lowlevel/xc/xc.c b/tools/python/xen/lowlevel/xc/xc.c
index ff714d79bb..d53870f956 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -1204,34 +1204,40 @@ static PyObject *pyxc_xeninfo(XcObject *self)
     xen_capabilities_info_t xen_caps;
     xen_platform_parameters_t p_parms;
     xen_commandline_t xen_commandline;
-    long xen_version;
-    long xen_pagesize;
+    xen_version_op_val_t xen_version;
+    xen_version_op_val_t xen_pagesize;
     char str[128];
 
-    xen_version = xc_version(self->xc_handle, XENVER_version, NULL);
-
-    if ( xc_version(self->xc_handle, XENVER_extraversion, &xen_extra) != 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_version, &xen_version,
+                    sizeof(xen_version)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
-    if ( xc_version(self->xc_handle, XENVER_compile_info, &xen_cc) != 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_extraversion, &xen_extra,
+                    sizeof(xen_extra)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
-    if ( xc_version(self->xc_handle, XENVER_changeset, &xen_chgset) != 0 )
+    memset(&xen_cc, 0, sizeof(xen_cc));
+
+    if ( xc_version(self->xc_handle, XEN_VERSION_changeset, &xen_chgset,
+                    sizeof(xen_chgset)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
-    if ( xc_version(self->xc_handle, XENVER_capabilities, &xen_caps) != 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_capabilities, &xen_caps,
+                    sizeof(xen_caps)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
-    if ( xc_version(self->xc_handle, XENVER_platform_parameters, &p_parms) != 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_platform_parameters,
+                    &p_parms, sizeof(p_parms)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
-    if ( xc_version(self->xc_handle, XENVER_commandline, &xen_commandline) != 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_commandline,
+                    &xen_commandline, sizeof(xen_commandline)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
     snprintf(str, sizeof(str), "virt_start=0x%"PRI_xen_ulong, p_parms.virt_start);
 
-    xen_pagesize = xc_version(self->xc_handle, XENVER_pagesize, NULL);
-    if (xen_pagesize < 0 )
+    if ( xc_version(self->xc_handle, XEN_VERSION_pagesize, &xen_pagesize,
+                    sizeof(xen_pagesize)) < 0 )
         return pyxc_error_to_exception(self->xc_handle);
 
     return Py_BuildValue("{s:i,s:i,s:s,s:s,s:i,s:s,s:s,s:s,s:s,s:s,s:s,s:s}",
diff --git a/tools/xenstat/libxenstat/src/xenstat.c b/tools/xenstat/libxenstat/src/xenstat.c
index 3495f3fcd7..efb68b5a63 100644
--- a/tools/xenstat/libxenstat/src/xenstat.c
+++ b/tools/xenstat/libxenstat/src/xenstat.c
@@ -621,20 +621,18 @@ unsigned long long xenstat_network_tdrop(xenstat_network * network)
 /* Collect Xen version information */
 static int xenstat_collect_xen_version(xenstat_node * node)
 {
-	long vnum = 0;
+	xen_version_op_val_t vnum = 0;
 	xen_extraversion_t version;
 
 	/* Collect Xen version information if not already collected */
 	if (node->handle->xen_version[0] == '\0') {
 		/* Get the Xen version number and extraversion string */
-		vnum = xc_version(node->handle->xc_handle,
-			XENVER_version, NULL);
-
-		if (vnum < 0)
+		if (xc_version(node->handle->xc_handle,
+			       XEN_VERSION_version, &vnum, sizeof(vnum)) < 0)
 			return 0;
 
-		if (xc_version(node->handle->xc_handle, XENVER_extraversion,
-			&version) < 0)
+		if (xc_version(node->handle->xc_handle, XEN_VERSION_extraversion,
+			       &version, sizeof(version)) < 0)
 			return 0;
 		/* Format the version information as a string and store it */
 		snprintf(node->handle->xen_version, VERSION_SIZE, "%ld.%ld%s",
diff --git a/tools/xentrace/xenctx.c b/tools/xentrace/xenctx.c
index e647179e19..cd280fc858 100644
--- a/tools/xentrace/xenctx.c
+++ b/tools/xentrace/xenctx.c
@@ -1000,7 +1000,8 @@ static void dump_ctx(int vcpu)
             guest_word_size = (cpuctx.msr_efer & 0x400) ? 8 :
                 guest_protected_mode ? 4 : 2;
             /* HVM guest context records are always host-sized */
-            if (xc_version(xenctx.xc_handle, XENVER_capabilities, &xen_caps) != 0) {
+            if (xc_version(xenctx.xc_handle, XEN_VERSION_capabilities,
+                           &xen_caps, sizeof(xen_caps)) < 0) {
                 perror("xc_version");
                 return;
             }