diff --git a/litellm/a2a_protocol/card_resolver.py b/litellm/a2a_protocol/card_resolver.py
index 8070d88b761..47d6346b9a6 100644
--- a/litellm/a2a_protocol/card_resolver.py
+++ b/litellm/a2a_protocol/card_resolver.py
@@ -67,11 +67,9 @@ def normalize_agent_card_protocol_bindings(agent_card: "AgentCard") -> "AgentCar
     case-sensitively against its uppercase TransportProtocol constants and fails
     with "no compatible transports found." for spec-adjacent casings.
     """
-    interfaces: Final = getattr(agent_card, "supported_interfaces", None) or ()
-    for interface in interfaces:
-        binding: str = getattr(interface, "protocol_binding", "") or ""
-        canonical = _CANONICAL_PROTOCOL_BINDINGS.get(binding.lower())
-        if canonical is not None and binding != canonical:
+    for interface in agent_card.supported_interfaces:
+        canonical: str | None = _CANONICAL_PROTOCOL_BINDINGS.get(interface.protocol_binding.lower())
+        if canonical is not None and canonical != interface.protocol_binding:
             interface.protocol_binding = canonical
     return agent_card
 
diff --git a/tests/test_litellm/a2a_protocol/test_main.py b/tests/test_litellm/a2a_protocol/test_main.py
index 29aa3aaabd7..aa988bc5b99 100644
--- a/tests/test_litellm/a2a_protocol/test_main.py
+++ b/tests/test_litellm/a2a_protocol/test_main.py
@@ -344,6 +344,7 @@ async def test_lowercase_protocol_binding_in_agent_card_still_gets_a_client(isol
     response = await _send_message(a2a_client, _send_request("lc"))
 
     assert type(response.root.result).__name__ == "Message"
+    assert a2a_client._litellm_agent_card.supported_interfaces[0].protocol_binding == "JSONRPC"
 
 
 @pytest.mark.asyncio