diff --git a/justfile b/justfile
index 05babb9..28389a7 100644
--- a/justfile
+++ b/justfile
@@ -31,7 +31,7 @@ logging-contract:
 # source precedence, root/inspect inheritance, and typed serve parsing.
 environment-contract:
     zig build -Doptimize=ReleaseSafe
-    python3 tests/environment_contract.py
+    STREAM_UPSTREAM_REPO='{{upstream}}' python3 tests/environment_contract.py
 
 # Offline: validate the vendored upstream Grafana dashboard and its parser.
 dashboard-test:
diff --git a/tests/environment_contract.py b/tests/environment_contract.py
index 0dcacd0..2a8469e 100644
--- a/tests/environment_contract.py
+++ b/tests/environment_contract.py
@@ -19,8 +19,15 @@ import urllib.request
 BIN = "./zig-out/bin/stream"
 PIN = "f29815c391fc2644f8a3dd36b899fb3697dd1ea6"
 ROOT = pathlib.Path(__file__).resolve().parents[1]
+# STREAM_UPSTREAM_REPO is the name the justfile, scripts/admit, and the other
+# oracles already use; this file was the only one reading JETSTREAM_UPSTREAM,
+# so on any box that does not lay the upstream out as ~/{forge}/{org}/{repo}
+# it looked for a checkout that was never there. JETSTREAM_UPSTREAM still wins
+# when set, for anyone who has it in their shell.
 UPSTREAM = pathlib.Path(
-    os.environ.get("JETSTREAM_UPSTREAM", pathlib.Path.home() / "github.com/bluesky-social/jetstream")
+    os.environ.get("JETSTREAM_UPSTREAM")
+    or os.environ.get("STREAM_UPSTREAM_REPO")
+    or (pathlib.Path.home() / "github.com/bluesky-social/jetstream")
 ).resolve()