diff --git a/tests/package.nix b/tests/package.nix
index e8e767ce5..1d50ab8d6 100644
--- a/tests/package.nix
+++ b/tests/package.nix
@@ -10,6 +10,14 @@ writeShellApplication {
     python3
     fzf
   ];
+  runtimeEnv = {
+    # Explicitly enable experimental features, in case someone runs e.g.
+    #   nix run .#tests --extra-experimental-features 'nix-command flakes'
+    # without enabling them globally.
+    NIX_CONFIG = ''
+      experimental-features = nix-command flakes
+    '';
+  };
   text = ''
     exec python3 ${flake}/tests/tests.py "$@"
   '';