diff --git a/dev-ml/xen-gnt/metadata.xml b/dev-ml/xen-gnt/metadata.xml
index e5f4c8ec96..ad55fc5375 100644
--- a/dev-ml/xen-gnt/metadata.xml
+++ b/dev-ml/xen-gnt/metadata.xml
@@ -8,4 +8,7 @@
   <upstream>
     <remote-id type="github">mirage/ocaml-gnt</remote-id>
   </upstream>
+  <use>
+    <flag name="unix">build the userspace library</flag>
+  </use>
 </pkgmetadata>
diff --git a/dev-ml/xen-gnt/xen-gnt-4.0.0.ebuild b/dev-ml/xen-gnt/xen-gnt-4.0.0.ebuild
index 843fe2e4cf..e7a1adc7f1 100644
--- a/dev-ml/xen-gnt/xen-gnt-4.0.0.ebuild
+++ b/dev-ml/xen-gnt/xen-gnt-4.0.0.ebuild
@@ -3,7 +3,7 @@
 
 EAPI=8
 
-inherit dune
+inherit dune multiprocessing
 
 DESCRIPTION="OCaml bindings to the Xen grant tables libraries"
 HOMEPAGE="https://github.com/mirage/ocaml-gnt"
@@ -13,19 +13,32 @@ S="${WORKDIR}/${PN}-v${PV}"
 LICENSE="ISC"
 SLOT="0/${PV}"
 KEYWORDS="~amd64"
-IUSE="ocamlopt"
+IUSE="ocamlopt unix"
 
 DEPEND="
 	dev-ml/cstruct
 	dev-ml/cmdliner
-	<=dev-ml/io-page-2.2.0
+	dev-ml/io-page
 	dev-ml/lwt
 	dev-ml/lwt-dllist
 	dev-ml/mirage-profile
+
+	unix? (
+		app-emulation/xen
+		dev-ml/io-page[unix(-)]
+	)
 "
 RDEPEND="${DEPEND}"
 
+src_compile() {
+	local pkgs="xen-gnt"
+	if use unix ; then
+		pkgs="${pkgs},xen-gnt-unix"
+	fi
+	dune build --only-packages "${pkgs}" -j $(makeopts_jobs) --profile release || die
+}
+
 src_install() {
 	dune_src_install xen-gnt
-	dune_src_install xen-gnt-unix
+	use unix && dune_src_install xen-gnt-unix
 }