diff --git a/setup-hermes.sh b/setup-hermes.sh
index f9b36a8cd0..969b82bef9 100755
--- a/setup-hermes.sh
+++ b/setup-hermes.sh
@@ -52,7 +52,7 @@ esac
 if [ "$os" = win32 ]; then
   # PROCESSOR_ARCHITECTURE lies under an emulated shell (x64 msys on a
   # WoA box reports AMD64); the registry carries the machine's truth.
-  winarch="$(reg.exe query 'HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' /v PROCESSOR_ARCHITECTURE 2>/dev/null | tr -d '\r' | awk '/PROCESSOR_ARCHITECTURE/ {print $NF}')"
+  winarch="$(MSYS2_ARG_CONV_EXCL='*' reg.exe query 'HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' /v PROCESSOR_ARCHITECTURE 2>/dev/null | tr -d '\r' | awk '/PROCESSOR_ARCHITECTURE/ {print $NF}')"
   case "${winarch:-${PROCESSOR_ARCHITECTURE:-}}" in
     ARM64) arch=arm64 ;;
     *) arch=x64 ;;
@@ -69,19 +69,20 @@ target="$os-$arch"
 # lock.json is machine-written (sorted keys, 2-space indent): read the uv
 # pin's version + this target's url/sha256 with awk — no python yet.
 pin() { # $1 = field (url | sha256)
-  awk -v target="$target" -v field="$1" '
+  awk -F '"' -v target="$target" -v field="$1" '
     /^    "uv": \{/ { in_uv = 1 }
-    in_uv && $0 ~ "^        \"" target "\": \\{" { in_t = 1 }
-    in_t && $0 ~ "^          \"" field "\":" {
-      gsub(/.*: "|,?$/, ""); print; exit
-    }' "$lock"
+    in_uv && /^    }/ { exit }
+    in_uv && /^        "/ { in_t = ($2 == target) }
+    in_t && $2 == field { print $4; exit }' "$lock"
 }
-uv_version="$(awk '
+uv_version="$(awk -F '"' '
   /^    "uv": \{/ { in_uv = 1 }
-  in_uv && /^      "version":/ { gsub(/.*: "|,?$/, ""); print; exit }' "$lock")"
-py_version="$(awk '
+  in_uv && /^    }/ { exit }
+  in_uv && $2 == "version" { print $4; exit }' "$lock")"
+py_version="$(awk -F '"' '
   /^    "python": \{/ { in_py = 1 }
-  in_py && /^      "version":/ { gsub(/.*: "|"$|",$/, ""); print; exit }' "$lock" \
+  in_py && /^    }/ { exit }
+  in_py && $2 == "version" { print $4; exit }' "$lock" \
   | cut -d+ -f1 | cut -d. -f1,2)"
 [ -n "$uv_version" ] || { echo -e "${RED}✗${NC} no uv pin in pm/lock.json" >&2; exit 1; }
 
diff --git a/tests/hermes_cli/test_setup_pin_values.py b/tests/hermes_cli/test_setup_pin_values.py
new file mode 100644
index 0000000000..75c91c26e7
--- /dev/null
+++ b/tests/hermes_cli/test_setup_pin_values.py
@@ -0,0 +1,58 @@
+"""Cold setup consumes lock values before executing any downloaded tool."""
+import json
+import os
+from pathlib import Path
+import shutil
+import subprocess
+
+import pytest
+
+from pm.store import current_target
+
+
+ROOT = Path(__file__).resolve().parents[2]
+
+
+@pytest.mark.platforms("windows", "posix")
+@pytest.mark.parametrize("missing_target", [False, True])
+def test_cold_setup_uses_exact_lock_values(tmp_path, missing_target):
+    checkout = tmp_path / "checkout"
+    (checkout / "pm").mkdir(parents=True)
+    shutil.copy2(ROOT / "setup-hermes.sh", checkout / "setup-hermes.sh")
+    lock = json.loads((ROOT / "pm" / "lock.json").read_text(encoding="utf-8"))
+    target = current_target()
+    uv_pin = lock["packages"]["uv"]
+    artifact = uv_pin["artifacts"][target]
+    if missing_target:
+        del uv_pin["artifacts"][target]
+    (checkout / "pm" / "lock.json").write_text(json.dumps(lock, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+    corrupt = tmp_path / "corrupt-download"
+    corrupt.write_bytes(b"intentional digest mismatch; this must never be executed\n")
+    args = tmp_path / "curl-args"
+    hook = tmp_path / "transport.sh"
+    hook.write_text('''curl() {
+    printf '%s\\n' "$@" > "$PROBE_ARGS"
+    while [ "$#" -gt 0 ]; do
+        if [ "$1" = -o ]; then
+            cp "$PROBE_DOWNLOAD" "$2"
+            return
+        fi
+        shift
+    done
+    return 37
+}
+''', encoding="utf-8")
+    env = dict(os.environ, HOME=tmp_path.as_posix(), HERMES_HOME=(tmp_path / "home").as_posix(),
+               HERMES_RUNTIME_DIR=(tmp_path / "tools").as_posix(), BASH_ENV=hook.as_posix(),
+               PROBE_ARGS=args.as_posix(), PROBE_DOWNLOAD=corrupt.as_posix())
+    result = subprocess.run(["bash", str(checkout / "setup-hermes.sh")], cwd=tmp_path,
+                            env=env, capture_output=True, text=True, encoding="utf-8", timeout=30)
+    assert result.returncode != 0, result.stdout + result.stderr
+    if missing_target:
+        assert not args.exists(), "a missing target must not select a sibling artifact"
+        assert f"no uv artifact for {target}" in result.stderr
+    else:
+        assert args.read_text(encoding="utf-8").splitlines()[-1] == artifact["url"]
+        assert f"pinned uv {uv_pin['version']} ({target})" in result.stdout
+        assert f"pinned {artifact['sha256']})" in result.stderr
+    assert not (checkout / ".env").exists()