diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 500904d2fa..fa3d61f1e8 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -1157,7 +1157,7 @@ static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_config *d_config,
     size_t fdt_size = 0;
     int pfdt_size = 0;
     libxl_domain_build_info *const info = &d_config->b_info;
-    bool iommu_created;
+    bool iommu_needed = false;
     unsigned int i;
 
     const libxl_version_info *vers;
@@ -1265,22 +1265,25 @@ next_resize:
         if (d_config->num_pcidevs)
             FDT( make_vpci_node(gc, fdt, ainfo, dom) );
 
-        iommu_created = false;
         for (i = 0; i < d_config->num_disks; i++) {
             libxl_device_disk *disk = &d_config->disks[i];
 
             if (disk->specification == LIBXL_DISK_SPECIFICATION_VIRTIO) {
-                if (disk->backend_domid != LIBXL_TOOLSTACK_DOMID &&
-                    !iommu_created) {
-                    FDT( make_xen_iommu_node(gc, fdt) );
-                    iommu_created = true;
-                }
+                if (disk->backend_domid != LIBXL_TOOLSTACK_DOMID)
+                    iommu_needed = true;
 
                 FDT( make_virtio_mmio_node(gc, fdt, disk->base, disk->irq,
                                            disk->backend_domid) );
             }
         }
 
+        /*
+         * The iommu node should be created only once for all virtio-mmio
+         * devices.
+         */
+        if (iommu_needed)
+            FDT( make_xen_iommu_node(gc, fdt) );
+
         if (pfdt)
             FDT( copy_partial_fdt(gc, fdt, pfdt) );