diff --git a/headroom/proxy/memory_handler.py b/headroom/proxy/memory_handler.py
index 9749c32c4..66d8b6db4 100644
--- a/headroom/proxy/memory_handler.py
+++ b/headroom/proxy/memory_handler.py
@@ -558,7 +558,7 @@ class MemoryHandler:
         # Check which tools are already present
         existing_names: set[str] = set()
         for tool in tools:
-            name = tool.get("name") or tool.get("function", {}).get("name")
+            name = tool.get("name") or (tool.get("function") or {}).get("name")
             if name:
                 existing_names.add(name)
 
@@ -1039,7 +1039,9 @@ your responses, not to drive new actions."""
         """Check if response contains memory tool calls."""
         tool_calls = self._extract_tool_calls(response, provider)
         for tc in tool_calls:
-            name = tc.get("name") or tc.get("function", {}).get("name")
+            # Coalesce `function` with `or {}` so an explicit {"function": null}
+            # on a malformed/partial upstream tool call doesn't crash detection.
+            name = tc.get("name") or (tc.get("function") or {}).get("name")
             # Check for both custom and native memory tools
             if name in MEMORY_TOOL_NAMES or name == NATIVE_MEMORY_TOOL_NAME:
                 return True
@@ -1106,7 +1108,11 @@ your responses, not to drive new actions."""
         results: list[dict[str, Any]] = []
 
         for tc in tool_calls:
-            tool_name = tc.get("name") or tc.get("function", {}).get("name")
+            # `tc.get("function", {})` returns None for an explicit
+            # {"function": null} (the default only applies to a missing key), so
+            # the following `.get` would raise AttributeError on a malformed /
+            # partial upstream tool call. Coalesce to {}.
+            tool_name = tc.get("name") or (tc.get("function") or {}).get("name")
             tool_id = tc.get("id") or tc.get("call_id", "")
 
             # Parse input data
@@ -1115,7 +1121,9 @@ your responses, not to drive new actions."""
             else:
                 # Chat Completions format: function.arguments
                 # Responses API format: arguments (top-level string)
-                args_str = tc.get("arguments") or tc.get("function", {}).get("arguments") or "{}"
+                args_str = (
+                    tc.get("arguments") or (tc.get("function") or {}).get("arguments") or "{}"
+                )
                 try:
                     input_data = json.loads(args_str)
                 except json.JSONDecodeError:
diff --git a/tests/test_memory_handler_null_function.py b/tests/test_memory_handler_null_function.py
new file mode 100644
index 000000000..66b3f1b62
--- /dev/null
+++ b/tests/test_memory_handler_null_function.py
@@ -0,0 +1,36 @@
+"""A tool call with a null ``function`` must not crash memory tool-call
+detection in ``MemoryHandler``.
+
+``tc.get("function", {}).get("name")`` raises ``AttributeError`` on an explicit
+``{"function": null}`` (the default only applies to a missing key). Both
+``has_memory_tool_calls`` and the arg extraction in ``handle_tool_calls`` read
+that shape from the untrusted upstream response. ``has_memory_tool_calls`` and
+``_extract_tool_calls`` use no instance state, so we exercise them on a bare
+instance via ``object.__new__``.
+"""
+
+from __future__ import annotations
+
+from headroom.proxy.memory_handler import MemoryHandler
+
+_handler = object.__new__(MemoryHandler)
+
+
+def _openai_response(tool_calls):
+    return {"choices": [{"message": {"tool_calls": tool_calls}}]}
+
+
+def test_has_memory_tool_calls_survives_null_function():
+    response = _openai_response(
+        [
+            {"id": "c1", "type": "function", "function": None},
+            {"id": "c2", "type": "function", "function": {"name": "memory_save"}},
+        ]
+    )
+    # Must not raise, and must still see the real memory tool call.
+    assert _handler.has_memory_tool_calls(response, "openai") is True
+
+
+def test_has_memory_tool_calls_all_null_functions_is_false():
+    response = _openai_response([{"id": "c1", "type": "function", "function": None}])
+    assert _handler.has_memory_tool_calls(response, "openai") is False