diff --git a/pkg/unikontainers/unikernels/mewz_test.go b/pkg/unikontainers/unikernels/mewz_test.go
new file mode 100644
index 00000000..7f1fff07
--- /dev/null
+++ b/pkg/unikontainers/unikernels/mewz_test.go
@@ -0,0 +1,107 @@
+// Copyright (c) 2023-2026, Nubificus LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package unikernels
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/urunc-dev/urunc/pkg/unikontainers/types"
+)
+
+func TestMewzReportsNoBlockOrFS(t *testing.T) {
+	m := newMewz()
+	assert.False(t, m.SupportsBlock())
+	for _, fs := range []string{"ext4", "9pfs", "virtiofs", "initrd", ""} {
+		assert.False(t, m.SupportsFS(fs))
+	}
+	assert.Nil(t, m.MonitorBlockCli())
+}
+
+func TestMewzCommandStringFormat(t *testing.T) {
+	m := &Mewz{
+		Net: MewzNet{Address: "10.0.0.2", Mask: 24, Gateway: "10.0.0.1"},
+	}
+	got, err := m.CommandString()
+	assert.NoError(t, err)
+	assert.Equal(t, "ip=10.0.0.2/24 gateway=10.0.0.1 ", got)
+}
+
+func TestMewzMonitorNetCli(t *testing.T) {
+	m := &Mewz{Monitor: "qemu"}
+	cli := m.MonitorNetCli("tap0", "aa:bb:cc:dd:ee:ff")
+	assert.Contains(t, cli, "virtio-net-pci")
+	assert.Contains(t, cli, "mac=aa:bb:cc:dd:ee:ff")
+	assert.Contains(t, cli, "ifname=tap0")
+	assert.Contains(t, cli, "id=net0")
+
+	for _, mon := range []string{"hvt", "spt", "firecracker", ""} {
+		assert.Empty(t, (&Mewz{Monitor: mon}).MonitorNetCli("tap0", "aa:bb:cc:dd:ee:ff"),
+			"monitor %q should not emit net cli", mon)
+	}
+}
+
+func TestMewzMonitorCli(t *testing.T) {
+	got := (&Mewz{Monitor: "qemu"}).MonitorCli()
+	assert.Contains(t, got.OtherArgs, "-no-reboot")
+	assert.Contains(t, got.OtherArgs, "isa-debug-exit")
+	assert.Empty(t, got.ExtraInitrd)
+
+	assert.Equal(t, types.MonitorCliArgs{}, (&Mewz{Monitor: "spt"}).MonitorCli())
+}
+
+func TestMewzInit(t *testing.T) {
+	t.Run("explicit mask is converted", func(t *testing.T) {
+		m := newMewz()
+		err := m.Init(types.UnikernelParams{
+			CmdLine: []string{"server", "--port=80"},
+			Monitor: "qemu",
+			Net: types.NetDevParams{
+				IP:      "192.168.1.10",
+				Mask:    "255.255.0.0",
+				Gateway: "192.168.1.1",
+			},
+		})
+		assert.NoError(t, err)
+		assert.Equal(t, "192.168.1.10", m.Net.Address)
+		assert.Equal(t, 16, m.Net.Mask)
+		assert.Equal(t, "192.168.1.1", m.Net.Gateway)
+		assert.Equal(t, "server --port=80", m.Command)
+		assert.Equal(t, "qemu", m.Monitor)
+	})
+
+	t.Run("missing mask defaults to /24", func(t *testing.T) {
+		m := newMewz()
+		err := m.Init(types.UnikernelParams{
+			CmdLine: []string{"server"},
+			Monitor: "qemu",
+			Net:     types.NetDevParams{IP: "10.0.0.2", Gateway: "10.0.0.1"},
+		})
+		assert.NoError(t, err)
+		assert.Equal(t, 24, m.Net.Mask)
+
+		out, _ := m.CommandString()
+		assert.True(t, strings.HasPrefix(out, "ip=10.0.0.2/24"))
+	})
+
+	t.Run("garbage mask returns error", func(t *testing.T) {
+		err := newMewz().Init(types.UnikernelParams{
+			Monitor: "qemu",
+			Net:     types.NetDevParams{IP: "10.0.0.2", Mask: "definitely.not.a.mask"},
+		})
+		assert.Error(t, err)
+	})
+}