diff --git a/openfut-protocol-blaze/fixtures/generate.py b/openfut-protocol-blaze/fixtures/generate.py
index 27d859c..050a3db 100644
--- a/openfut-protocol-blaze/fixtures/generate.py
+++ b/openfut-protocol-blaze/fixtures/generate.py
@@ -55,6 +55,21 @@ sys.path.insert(0, TOOLS)
 # staleness guard into a no-op that always rewrites and always passes.
 CHECK_ONLY = "--check" in sys.argv[1:]
 sys.argv = [sys.argv[0]]
+
+# Pin the deployment-dependent config BEFORE importing the responder, which
+# reads these at import time. Several live payloads embed the advertised
+# address (Blaze redirect target, RS4/POW/roster URLs), so without this the
+# fixture bytes would depend on whoever's shell ran the generator and `--check`
+# would go red on a machine that happens to export OPENFUT_ADVERTISE.
+#
+# 127.0.0.1 is a placeholder chosen so no real LAN address is ever baked into a
+# committed fixture. It is NOT a statement about how the backend is deployed —
+# remote mode requires an explicit advertised address and has no loopback
+# fallback (see the vault's Architecture note on OPENFUT_BIND vs
+# OPENFUT_ADVERTISE).
+os.environ["OPENFUT_ADVERTISE"] = "127.0.0.1"
+os.environ["OPENFUT_BIND"] = "127.0.0.1"
+
 import heat2  # noqa: E402
 import blaze_responder_v3b as B  # noqa: E402