diff --git a/crates/xen/xencall/src/lib.rs b/crates/xen/xencall/src/lib.rs
index f2496db..4e606f3 100644
--- a/crates/xen/xencall/src/lib.rs
+++ b/crates/xen/xencall/src/lib.rs
@@ -98,7 +98,7 @@ impl XenCall {
                 value: SysctlValue {
                     cputopoinfo: SysctlCputopoinfo {
                         num_cpus: 0,
-                        handle: null_mut(),
+                        handle: 0,
                     },
                 },
             };
@@ -958,7 +958,7 @@ impl XenCall {
             value: SysctlValue {
                 cputopoinfo: SysctlCputopoinfo {
                     num_cpus: 0,
-                    handle: null_mut(),
+                    handle: 0,
                 },
             },
         };
@@ -979,7 +979,7 @@ impl XenCall {
             value: SysctlValue {
                 cputopoinfo: SysctlCputopoinfo {
                     num_cpus: cpus,
-                    handle: topos.as_mut_ptr(),
+                    handle: topos.as_mut_ptr() as c_ulong,
                 },
             },
         };
diff --git a/crates/xen/xencall/src/sys.rs b/crates/xen/xencall/src/sys.rs
index 32ca833..0918280 100644
--- a/crates/xen/xencall/src/sys.rs
+++ b/crates/xen/xencall/src/sys.rs
@@ -747,7 +747,7 @@ pub struct SysctlPmOp {
 #[derive(Clone, Copy, Debug)]
 pub struct SysctlCputopoinfo {
     pub num_cpus: u32,
-    pub handle: *mut SysctlCputopo,
+    pub handle: c_ulong,
 }
 
 #[repr(C)]