diff --git a/README.md b/README.md
index 42ae35c..efff072 100644
--- a/README.md
+++ b/README.md
@@ -232,17 +232,30 @@ direnv_layout_dir() {
 During direnv setup `direnv_layout_dir` can be called multiple times and with different values of `$PWD`
 (when other `.envrc` files are included). Therefore cache its results in dictionary `direnv_layout_dirs`.
 
-## Manually re-triggering evaluation
+## Watching additional files
 
-In some case nix-direnv does not detect if imported file has changed and still
-provides the old cached values. An evaluation can be triggered by updating your
-`default.nix`, `shell.nix` or `flake.nix`, depending on what is used:
+To minimize the number of evaluations, nix-direnv maintains a list of files to check
+for changes when deciding if an update of the cached environment is required. By default, `use_flake` watches
 
-```console
-# choose one
-$ touch default.nix
-$ touch shell.nix
-$ touch flake.nix
+```
+flake.nix
+flake.lock
+devshell.toml
+```
+
+`use_nix` watches
+
+```
+default.nix
+shell.nix
+```
+
+To trigger an evaluation when other nix files change, register them by calling `nix_direnv_watch_file PATH [PATH...]` from `.envrc`.
+
+```bash
+nix_direnv_watch_file module.nix
+nix_direnv_watch_file mod1.nix mod2.nix
+use flake
 ```
 
 ## Shell integration
diff --git a/direnvrc b/direnvrc
index 46c4691..1435719 100644
--- a/direnvrc
+++ b/direnvrc
@@ -111,6 +111,11 @@ _nix_argsum_suffix() {
   fi
 }
 
+nix_direnv_watch_file() {
+  watch_file "$@"
+  nix_watches+=("$@")
+}
+
 use_flake() {
   flake_expr="${1:-.}"
   flake_dir="${flake_expr%#*}"
@@ -123,13 +128,25 @@ use_flake() {
   local flake_inputs="${layout_dir}/flake-inputs/"
   local profile_rc="${profile}.rc"
 
+  nix_watches+=(
+      "$HOME/".direnvrc
+      .envrc
+      "$flake_dir/"devshell.toml
+      "$flake_dir/"flake.nix
+      "$flake_dir/"flake.lock
+  )
+
+  need_update=0
+  for file in "${nix_watches[@]}"; do
+    if [[ "$file" -nt "$profile_rc" ]]; then
+      need_update=1
+      break
+    fi
+  done
+
   if [[ ! -e "$profile"
      || ! -e "$profile_rc"
-     || "$HOME/.direnvrc" -nt "$profile_rc"
-     || .envrc -nt "$profile_rc"
-     || "$flake_dir/"devshell.toml -nt "$profile_rc"
-     || "$flake_dir/"flake.nix -nt "$profile_rc"
-     || "$flake_dir/"flake.lock -nt "$profile_rc"
+     || "$need_update" -eq "1"
      ]];
   then
     local tmp_profile="${layout_dir}/flake-profile.$$"
@@ -239,12 +256,24 @@ use_nix() {
   local cache
   cache="${layout_dir}/cache-${version:-unknown}$(_nix_argsum_suffix "$*")"
 
+  nix_watches+=(
+      "$HOME/".direnvrc
+      .envrc
+      default.nix
+      shell.nix
+  )
+
+  need_update=0
+  for file in "${nix_watches[@]}"; do
+    if [[ "$file" -nt "$cache" ]]; then
+      need_update=1
+      break
+    fi
+  done
+
   local update_drv=0
   if [[ ! -e "$cache"
-     || "$HOME/.direnvrc" -nt "$cache"
-     || .envrc -nt "$cache"
-     || default.nix -nt "$cache"
-     || shell.nix -nt "$cache"
+     || "$need_update" -eq "1"
      ]];
   then
     [[ -d "$layout_dir" ]] || mkdir -p "$layout_dir"