diff --git a/test/dm/iommu.c b/test/dm/iommu.c
new file mode 100644
index 0000000..94174a7
--- /dev/null
+++ b/test/dm/iommu.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Mark Kettenis <kettenis@openbsd.org>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/test.h>
+#include <dm/uclass-internal.h>
+#include <iommu.h>
+#include <test/test.h>
+#include <test/ut.h>
+
+static int dm_test_iommu(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+
+	ut_assertok(uclass_find_device(UCLASS_IOMMU, 0, &dev));
+	ut_assert(!(dev_get_flags(dev) & DM_FLAG_ACTIVATED));
+
+	/* Probing USB probes the IOMMU through the "iommus" property */
+	ut_assertok(uclass_probe_all(UCLASS_USB));
+	ut_assert(dev_get_flags(dev) & DM_FLAG_ACTIVATED);
+
+	return 0;
+}
+
+DM_TEST(dm_test_iommu, UT_TESTF_SCAN_FDT);