diff --git a/packages/google-auth/google/auth/compute_engine/_metadata.py b/packages/google-auth/google/auth/compute_engine/_metadata.py
index aae724ab18ee..ad7438dbd6d7 100644
--- a/packages/google-auth/google/auth/compute_engine/_metadata.py
+++ b/packages/google-auth/google/auth/compute_engine/_metadata.py
@@ -174,9 +174,9 @@ def _prepare_request_for_mds(request, use_mtls=False) -> None:
 
     """
     # Only modify the request if mTLS is enabled, and request supports sessions.
-    if use_mtls and hasattr(request, "session"):
+    if use_mtls:
         # Ensure the request has a session to mount the adapter to.
-        if not request.session:
+        if not hasattr(request, "session") or not request.session:
             request.session = requests.Session()
 
         adapter = _mtls.MdsMtlsAdapter()