diff --git a/third_party/blink/renderer/bindings/scripts/bind_gen/interface.py b/third_party/blink/renderer/bindings/scripts/bind_gen/interface.py
index 6a42e2517d089..4ccd21bfd1f7b 100644
--- a/third_party/blink/renderer/bindings/scripts/bind_gen/interface.py
+++ b/third_party/blink/renderer/bindings/scripts/bind_gen/interface.py
@@ -2483,12 +2483,14 @@ def make_no_alloc_direct_call_callback_def(cg_context, function_name,
                           "${v8_arg0_receiver};")),
         S("handle_scope", "v8::HandleScope handle_scope(${isolate});")
     ])
-    # NADC stubs won't have any JS re-entry during argument conversion, so
-    # skip detach check for PassAsSpan arguments.
+    # NADC stubs that accept v8::Local<v8::Value> for [PassAsSpan] arguments
+    # *can* re-enter JS via the IDL sequence<> fallback (Symbol.iterator), so
+    # the ArrayBuffer detach check must remain enabled. It is a single boolean
+    # check on a v8::Local that is already held; the cost is negligible.
     body.register_code_symbol(
         S(
             "kPerformDetachCheckFlag",
-            "constexpr auto kPerformDetachCheckFlag = PassAsSpanMarkerBase::Flags::kNone;"
+            "constexpr auto kPerformDetachCheckFlag = PassAsSpanMarkerBase::Flags::kPerformDetachCheck;"
         ))
 
     bind_callback_local_vars(body, cg_context)