diff --git a/.github/workflows/config-options-check.yml b/.github/workflows/config-options-check.yml
index 65a9f92..e6ab630 100644
--- a/.github/workflows/config-options-check.yml
+++ b/.github/workflows/config-options-check.yml
@@ -12,6 +12,9 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Verify flake.lock owners
+        run: scripts/check-flake-lock-owners.sh
+
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v13
 
diff --git a/scripts/allowed-flake-lock-owners.txt b/scripts/allowed-flake-lock-owners.txt
new file mode 100644
index 0000000..04b6446
--- /dev/null
+++ b/scripts/allowed-flake-lock-owners.txt
@@ -0,0 +1,6 @@
+# Allowed GitHub inputs in flake.lock (owner/repo)
+NixOS/nixpkgs
+moltbot/nix-steipete-tools
+nix-community/home-manager
+nix-systems/default
+numtide/flake-utils
diff --git a/scripts/check-flake-lock-owners.sh b/scripts/check-flake-lock-owners.sh
new file mode 100755
index 0000000..a530365
--- /dev/null
+++ b/scripts/check-flake-lock-owners.sh
@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+lock_file=${1:-flake.lock}
+allow_file=${2:-scripts/allowed-flake-lock-owners.txt}
+
+if ! command -v jq >/dev/null 2>&1; then
+  echo "jq is required but not installed" >&2
+  exit 1
+fi
+
+if [[ ! -f "$lock_file" ]]; then
+  echo "flake.lock not found: $lock_file" >&2
+  exit 1
+fi
+
+if [[ ! -f "$allow_file" ]]; then
+  echo "allowlist not found: $allow_file" >&2
+  exit 1
+fi
+
+mapfile -t allowed < <(
+  sed -e 's/#.*$//' -e 's/[[:space:]]*$//' -e 's/^[[:space:]]*//' "$allow_file" | awk 'NF' | sort -u
+)
+
+if [[ ${#allowed[@]} -eq 0 ]]; then
+  echo "allowlist is empty: $allow_file" >&2
+  exit 1
+fi
+
+mapfile -t owners < <(
+  jq -r '.nodes[].locked | select(.type == "github") | "\(.owner)/\(.repo)"' "$lock_file" | sort -u
+)
+
+unknown=()
+for owner in "${owners[@]}"; do
+  if ! printf '%s\n' "${allowed[@]}" | grep -Fxq "$owner"; then
+    unknown+=("$owner")
+  fi
+done
+
+if [[ ${#unknown[@]} -ne 0 ]]; then
+  echo "Unexpected GitHub inputs found in $lock_file:" >&2
+  printf '  - %s\n' "${unknown[@]}" >&2
+  exit 1
+fi
+
+echo "OK: flake.lock GitHub owners are allowlisted"