diff --git a/test/nixos-search/ci-test.sh b/test/nixos-search/ci-test.sh
index 8580a93..1f28361 100755
--- a/test/nixos-search/ci-test.sh
+++ b/test/nixos-search/ci-test.sh
@@ -3,13 +3,19 @@ set -euo pipefail
 
 cd "${BASH_SOURCE[0]%/*}"
 
+nbFlake=$(realpath ../..)
+
 # Use cachix to cache the `flake-info` build
 cachixCache=nix-bitcoin
 
 nix run .#cachix -- use "$cachixCache"
 
 # shellcheck disable=SC2016
-PATH=$(nix shell -L .#flake-info .#cachix -c sh -c 'echo $PATH')
+PATH=$(nix shell -L .#{flake-info,cachix,jq} -c sh -c 'echo $PATH')
+
+# flake-info uses `nixpkgs` from NIX_PATH
+NIX_PATH="nixpkgs=$(nix flake metadata --json --inputs-from "$nbFlake" nixpkgs | jq -r .path)"
+export NIX_PATH
 
 if [[ ${CACHIX_SIGNING_KEY:-} ]]; then
     cachix push "$cachixCache" "$(type -P flake-info)";
diff --git a/test/nixos-search/flake-info-sandboxed.sh b/test/nixos-search/flake-info-sandboxed.sh
index 2bf6bb8..aeb8199 100755
--- a/test/nixos-search/flake-info-sandboxed.sh
+++ b/test/nixos-search/flake-info-sandboxed.sh
@@ -13,7 +13,11 @@ cd "${BASH_SOURCE[0]%/*}"
 nbFlake=$(realpath ../..)
 
 # shellcheck disable=SC2016
-PATH=$(nix shell -L .#{flake-info,bubblewrap} -c sh -c 'echo $PATH')
+PATH=$(nix shell -L .#{flake-info,bubblewrap,jq} -c sh -c 'echo $PATH')
+
+# flake-info uses `nixpkgs` from NIX_PATH
+NIX_PATH="nixpkgs=$(nix flake metadata --json --inputs-from "$nbFlake" nixpkgs | jq -r .path)"
+export NIX_PATH
 
 tmpDir=$(mktemp -d /tmp/nix-bitcoin-flake-info.XXX)
 trap 'rm -rf $tmpDir' EXIT
diff --git a/test/nixos-search/flake.nix b/test/nixos-search/flake.nix
index 8c462bc..a4e816f 100644
--- a/test/nixos-search/flake.nix
+++ b/test/nixos-search/flake.nix
@@ -4,8 +4,24 @@
 {
   inputs.nixos-search.url = "github:nixos/nixos-search";
 
-  outputs = { self, nixos-search }: {
-    inherit (nixos-search) packages;
+  outputs = { self, nixos-search }: let
+    systems = [
+      "x86_64-linux"
+      "aarch64-linux"
+    ];
+    inherit (nixos-search.inputs.nixpkgs) lib;
+  in {
+    packages = lib.genAttrs systems (system: {
+      # In flake-info, Rust calls into Nix code which uses `nixpkgs` from NIX_PATH.
+      # Don't set `nixpkgs` to a tarball URL, use the default value from the environment instead.
+      # This allows running flake-info in an offline environment (./flake-info-sandboxed.sh).
+      flake-info = nixos-search.packages.${system}.flake-info.overrideAttrs (old: {
+        postPatch = (old.postPatch or "") + ''
+          substituteInPlace src/commands/nix_flake_attrs.rs --replace-fail \
+            'command.add_arg_pair("-I", "nixpkgs=https://github.com/NixOS/nixpkgs/archive/refs/heads/nixpkgs-unstable.tar.gz");' ""
+        '';
+      });
+    });
 
     # Used by ./ci-test.sh
     inherit (nixos-search.inputs.nixpkgs) legacyPackages;