diff --git a/keystore2/src/km_compat.rs b/keystore2/src/km_compat.rs
index 035edd9..8eba02d 100644
--- a/keystore2/src/km_compat.rs
+++ b/keystore2/src/km_compat.rs
@@ -32,6 +32,11 @@
 use anyhow::Context;
 use keystore2_crypto::{hmac_sha256, HMAC_SHA256_LEN};
 
+/// Magic prefix used by the km_compat C++ code to mark a key that is owned by an
+/// underlying Keymaster hardware device that has been wrapped by km_compat. (The
+/// final zero byte indicates that the blob is not software emulated.)
+pub const KEYMASTER_BLOB_HW_PREFIX: &[u8] = b"pKMblob\x00";
+
 /// Key data associated with key generation/import.
 #[derive(Debug, PartialEq, Eq)]
 pub enum KeyImportData<'a> {
diff --git a/keystore2/src/legacy_importer.rs b/keystore2/src/legacy_importer.rs
index 325c213..159e936 100644
--- a/keystore2/src/legacy_importer.rs
+++ b/keystore2/src/legacy_importer.rs
@@ -914,11 +914,12 @@
     uuid: &Uuid,
     blob: &[u8],
 ) -> Result<(Vec<KeyParameter>, Option<Vec<u8>>)> {
-    let (km_dev, _) = crate::globals::get_keymint_dev_by_uuid(uuid)
+    let (km_dev, info) = crate::globals::get_keymint_dev_by_uuid(uuid)
         .with_context(|| ks_err!("Trying to get km device for id {:?}", uuid))?;
 
     let (characteristics, upgraded_blob) = upgrade_keyblob_if_required_with(
         &*km_dev,
+        info.versionNumber,
         blob,
         &[],
         |blob| {
diff --git a/keystore2/src/raw_device.rs b/keystore2/src/raw_device.rs
index 860a1bc..44d805c 100644
--- a/keystore2/src/raw_device.rs
+++ b/keystore2/src/raw_device.rs
@@ -265,6 +265,7 @@
     {
         let (f_result, upgraded_blob) = crate::utils::upgrade_keyblob_if_required_with(
             &*self.km_dev,
+            self.version(),
             &key_blob,
             &[],
             f,
diff --git a/keystore2/src/rkpd_client.rs b/keystore2/src/rkpd_client.rs
index 938d389..7b4131d 100644
--- a/keystore2/src/rkpd_client.rs
+++ b/keystore2/src/rkpd_client.rs
@@ -666,7 +666,7 @@
     fn test_rkpd_attestation_key_upgrade() {
         binder::ProcessState::start_thread_pool();
         let security_level = SecurityLevel::TRUSTED_ENVIRONMENT;
-        let (keymint, _, _) = get_keymint_device(&security_level).unwrap();
+        let (keymint, info, _) = get_keymint_device(&security_level).unwrap();
         let key_id = get_next_key_id();
         let mut key_upgraded = false;
 
@@ -676,6 +676,7 @@
 
         upgrade_keyblob_if_required_with(
             &*keymint,
+            info.versionNumber,
             &key.keyBlob,
             /*upgrade_params=*/ &[],
             /*km_op=*/
diff --git a/keystore2/src/security_level.rs b/keystore2/src/security_level.rs
index db44d4b..44ca4c8 100644
--- a/keystore2/src/security_level.rs
+++ b/keystore2/src/security_level.rs
@@ -317,7 +317,6 @@
 
         let (begin_result, upgraded_blob) = self
             .upgrade_keyblob_if_required_with(
-                &*self.keymint,
                 key_id_guard,
                 &km_blob,
                 blob_metadata.km_uuid().copied(),
@@ -561,7 +560,6 @@
                 issuer_subject,
             }) => self
                 .upgrade_keyblob_if_required_with(
-                    &*self.keymint,
                     Some(key_id_guard),
                     &KeyBlob::Ref(&blob),
                     blob_metadata.km_uuid().copied(),
@@ -786,7 +784,6 @@
 
         let (creation_result, _) = self
             .upgrade_keyblob_if_required_with(
-                &*self.keymint,
                 Some(wrapping_key_id_guard),
                 &wrapping_key_blob,
                 wrapping_blob_metadata.km_uuid().copied(),
@@ -842,7 +839,6 @@
 
     fn upgrade_keyblob_if_required_with<T, F>(
         &self,
-        km_dev: &dyn IKeyMintDevice,
         mut key_id_guard: Option<KeyIdGuard>,
         key_blob: &KeyBlob,
         km_uuid: Option<Uuid>,
@@ -853,7 +849,8 @@
         F: Fn(&[u8]) -> Result<T, Error>,
     {
         let (v, upgraded_blob) = crate::utils::upgrade_keyblob_if_required_with(
-            km_dev,
+            &*self.keymint,
+            self.hw_info.versionNumber,
             key_blob,
             params,
             f,
@@ -893,6 +890,7 @@
     {
         crate::utils::upgrade_keyblob_if_required_with(
             &*self.keymint,
+            self.hw_info.versionNumber,
             key_blob,
             params,
             f,
diff --git a/keystore2/src/utils.rs b/keystore2/src/utils.rs
index 584a51c..80aa7c3 100644
--- a/keystore2/src/utils.rs
+++ b/keystore2/src/utils.rs
@@ -23,6 +23,8 @@
 use crate::{
     database::{KeyType, KeystoreDB},
     globals::LEGACY_IMPORTER,
+    km_compat,
+    raw_device::KeyMintDevice,
 };
 use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{
     IKeyMintDevice::IKeyMintDevice, KeyCharacteristics::KeyCharacteristics,
@@ -163,13 +165,9 @@
         .collect()
 }
 
-/// This function can be used to upgrade key blobs on demand. The return value of
-/// `km_op` is inspected and if ErrorCode::KEY_REQUIRES_UPGRADE is encountered,
-/// an attempt is made to upgrade the key blob. On success `new_blob_handler` is called
-/// with the upgraded blob as argument. Then `km_op` is called a second time with the
-/// upgraded blob as argument. On success a tuple of the `km_op`s result and the
-/// optional upgraded blob is returned.
-pub fn upgrade_keyblob_if_required_with<T, KmOp, NewBlobHandler>(
+/// Upgrade a keyblob then invoke both the `new_blob_handler` and the `km_op` closures.  On success
+/// a tuple of the `km_op`s result and the optional upgraded blob is returned.
+fn upgrade_keyblob_and_perform_op<T, KmOp, NewBlobHandler>(
     km_dev: &dyn IKeyMintDevice,
     key_blob: &[u8],
     upgrade_params: &[KmKeyParameter],
@@ -180,22 +178,75 @@
     KmOp: Fn(&[u8]) -> Result<T, Error>,
     NewBlobHandler: FnOnce(&[u8]) -> Result<()>,
 {
+    let upgraded_blob = {
+        let _wp = watchdog::watch_millis(
+            "In utils::upgrade_keyblob_and_perform_op: calling upgradeKey.",
+            500,
+        );
+        map_km_error(km_dev.upgradeKey(key_blob, upgrade_params))
+    }
+    .context(ks_err!("Upgrade failed."))?;
+
+    new_blob_handler(&upgraded_blob).context(ks_err!("calling new_blob_handler."))?;
+
+    km_op(&upgraded_blob)
+        .map(|v| (v, Some(upgraded_blob)))
+        .context(ks_err!("Calling km_op after upgrade."))
+}
+
+/// This function can be used to upgrade key blobs on demand. The return value of
+/// `km_op` is inspected and if ErrorCode::KEY_REQUIRES_UPGRADE is encountered,
+/// an attempt is made to upgrade the key blob. On success `new_blob_handler` is called
+/// with the upgraded blob as argument. Then `km_op` is called a second time with the
+/// upgraded blob as argument. On success a tuple of the `km_op`s result and the
+/// optional upgraded blob is returned.
+pub fn upgrade_keyblob_if_required_with<T, KmOp, NewBlobHandler>(
+    km_dev: &dyn IKeyMintDevice,
+    km_dev_version: i32,
+    key_blob: &[u8],
+    upgrade_params: &[KmKeyParameter],
+    km_op: KmOp,
+    new_blob_handler: NewBlobHandler,
+) -> Result<(T, Option<Vec<u8>>)>
+where
+    KmOp: Fn(&[u8]) -> Result<T, Error>,
+    NewBlobHandler: FnOnce(&[u8]) -> Result<()>,
+{
     match km_op(key_blob) {
-        Err(Error::Km(ErrorCode::KEY_REQUIRES_UPGRADE)) => {
-            let upgraded_blob = {
-                let _wp = watchdog::watch_millis(
-                    "In utils::upgrade_keyblob_if_required_with: calling upgradeKey.",
-                    500,
-                );
-                map_km_error(km_dev.upgradeKey(key_blob, upgrade_params))
-            }
-            .context(ks_err!("Upgrade failed."))?;
-
-            new_blob_handler(&upgraded_blob).context(ks_err!("calling new_blob_handler."))?;
-
-            km_op(&upgraded_blob)
-                .map(|v| (v, Some(upgraded_blob)))
-                .context(ks_err!("Calling km_op after upgrade."))
+        Err(Error::Km(ErrorCode::KEY_REQUIRES_UPGRADE)) => upgrade_keyblob_and_perform_op(
+            km_dev,
+            key_blob,
+            upgrade_params,
+            km_op,
+            new_blob_handler,
+        ),
+        // Some devices have been known to upgrade their Keymaster device to be a KeyMint
+        // device with a new release of Android.  If this is the case, then any pre-upgrade
+        // keyblobs will have the km_compat prefix attached to them.
+        //
+        // This prefix gets stripped by the km_compat layer when used pre-upgrade, but after
+        // the upgrade the keyblob will be passed as-is to the KeyMint device, which probably
+        // won't expect to see the km_compat prefix.
+        //
+        // So if a keyblob:
+        //   a) gets rejected with INVALID_KEY_BLOB
+        //   b) when sent to a KeyMint (not km_compat) device
+        //   c) and has the km_compat magic prefix
+        //   d) and was not a software-emulated key pre-upgrade
+        // then strip the prefix and attempt a key upgrade.
+        Err(Error::Km(ErrorCode::INVALID_KEY_BLOB))
+            if km_dev_version >= KeyMintDevice::KEY_MINT_V1
+                && key_blob.starts_with(km_compat::KEYMASTER_BLOB_HW_PREFIX) =>
+        {
+            log::info!("found apparent km_compat(Keymaster) blob, attempt strip-and-upgrade");
+            let inner_keyblob = &key_blob[km_compat::KEYMASTER_BLOB_HW_PREFIX.len()..];
+            upgrade_keyblob_and_perform_op(
+                km_dev,
+                inner_keyblob,
+                upgrade_params,
+                km_op,
+                new_blob_handler,
+            )
         }
         r => r.map(|v| (v, None)).context(ks_err!("Calling km_op.")),
     }