diff --git a/.gitignore b/.gitignore
index 7ad6275..8454dc7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1 @@
-/.direnv
+/nim.cfg
diff --git a/Tupfile b/Tupfile
new file mode 100644
index 0000000..b7acbb1
--- /dev/null
+++ b/Tupfile
@@ -0,0 +1,3 @@
+include_rules
+: |> !nim_lk |> lock.json
+: lock.json |> !nim_cfg |> | ./<lock>
diff --git a/Tuprules.tup b/Tuprules.tup
index 74f1fe4..d37c1ce 100644
--- a/Tuprules.tup
+++ b/Tuprules.tup
@@ -1,4 +1,5 @@
 include ../syndicate-nim/depends.tup
+NIM = $(DIRENV) $(NIM)
 NIM_FLAGS += --path:$(TUP_CWD)/../syndicate-nim/src
 NIM_FLAGS += --path:$(TUP_CWD)/../genode-nim/src
-NIM = /nix/store/zp7f2j6lsas1rfi0v2rx51c29c00xnz9-x86_64-unknown-genode-nim-wrapper-1.6.8-x86_64-unknown-genode/bin/nim
+NIM_GROUPS += $(TUP_CWD)/<lock>