diff --git a/src/borg/crypto/key.py b/src/borg/crypto/key.py
index a45c6c7953..338888b3af 100644
--- a/src/borg/crypto/key.py
+++ b/src/borg/crypto/key.py
@@ -246,6 +246,8 @@ def unpack_and_verify_manifest(self, data, force_tam_not_required=False):
         unpacker = get_limited_unpacker("manifest")
         unpacker.feed(data)
         unpacked = unpacker.unpack()
+        if AUTHENTICATED_NO_KEY:
+            return unpacked, True  # True is a lie.
         if "tam" not in unpacked:
             if tam_required:
                 raise TAMRequiredError(self.repository._location.canonical_path())
@@ -271,8 +273,6 @@ def unpack_and_verify_manifest(self, data, force_tam_not_required=False):
         offset = data.index(tam_hmac)
         data[offset : offset + 64] = bytes(64)
         tam_key = self._tam_key(tam_salt, context=b"manifest")
-        if AUTHENTICATED_NO_KEY:
-            return unpacked, True  # True is a lie.
         calculated_hmac = hmac.digest(tam_key, data, "sha512")
         if not hmac.compare_digest(calculated_hmac, tam_hmac):
             raise TAMInvalid()