diff --git a/microdroid/README.md b/microdroid/README.md
index ebf2244..7084773 100644
--- a/microdroid/README.md
+++ b/microdroid/README.md
@@ -57,34 +57,18 @@
           "path": "/apex/com.android.virt/etc/fs/microdroid_boot-5.10.img"
         },
         {
-          "label": "boot_b",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_boot-5.10.img"
-        },
-        {
           "label": "vendor_boot_a",
           "path": "/apex/com.android.virt/etc/fs/microdroid_vendor_boot-5.10.img"
         },
         {
-          "label": "vendor_boot_b",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_vendor_boot-5.10.img"
-        },
-        {
           "label": "vbmeta_a",
           "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta.img"
         },
         {
-          "label": "vbmeta_b",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta.img"
-        },
-        {
           "label": "vbmeta_system_a",
           "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta_system.img"
         },
         {
-          "label": "vbmeta_system_b",
-          "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta_system.img"
-        },
-        {
           "label": "super",
           "path": "/apex/com.android.virt/etc/fs/microdroid_super.img"
         }
diff --git a/microdroid/microdroid_cdisk.json b/microdroid/microdroid_cdisk.json
index 5e3c9c5..d0a5025 100644
--- a/microdroid/microdroid_cdisk.json
+++ b/microdroid/microdroid_cdisk.json
@@ -5,34 +5,18 @@
       "path": "/apex/com.android.virt/etc/fs/microdroid_boot-5.10.img"
     },
     {
-      "label": "boot_b",
-      "path": "/apex/com.android.virt/etc/fs/microdroid_boot-5.10.img"
-    },
-    {
       "label": "vendor_boot_a",
       "path": "/apex/com.android.virt/etc/fs/microdroid_vendor_boot-5.10.img"
     },
     {
-      "label": "vendor_boot_b",
-      "path": "/apex/com.android.virt/etc/fs/microdroid_vendor_boot-5.10.img"
-    },
-    {
       "label": "vbmeta_a",
       "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta.img"
     },
     {
-      "label": "vbmeta_b",
-      "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta.img"
-    },
-    {
       "label": "vbmeta_system_a",
       "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta_system.img"
     },
     {
-      "label": "vbmeta_system_b",
-      "path": "/apex/com.android.virt/etc/fs/microdroid_vbmeta_system.img"
-    },
-    {
       "label": "super",
       "path": "/apex/com.android.virt/etc/fs/microdroid_super.img"
     }
diff --git a/microdroid/uboot-env-x86_64.txt b/microdroid/uboot-env-x86_64.txt
index dfa6a98..1abafa6 100644
--- a/microdroid/uboot-env-x86_64.txt
+++ b/microdroid/uboot-env-x86_64.txt
@@ -1,7 +1,9 @@
 # Static u-boot environment variables for microdroid. See b/180481192
 
 # Boot the device following the Android boot procedure
-bootcmd=avb init virtio 0 && avb verify _a && boot_android virtio 0
+# `0` is the disk number of os_composite.img
+# `a` and `_a` are the slot index for A/B
+bootcmd=avb init virtio 0 && avb verify _a && boot_android virtio 0 a
 
 bootdelay=0
 
diff --git a/microdroid/uboot-env.txt b/microdroid/uboot-env.txt
index 47b8f2c..585702e 100644
--- a/microdroid/uboot-env.txt
+++ b/microdroid/uboot-env.txt
@@ -1,7 +1,9 @@
 # Static u-boot environment variables for microdroid. See b/180481192
 
 # Boot the device following the Android boot procedure
-bootcmd=avb init virtio 0 && avb verify _a && boot_android virtio 0
+# `0` is the disk number of os_composite.img
+# `a` and `_a` are the slot index for A/B
+bootcmd=avb init virtio 0 && avb verify _a && boot_android virtio 0 a
 
 bootdelay=0
 fdtaddr=0x80000000