diff --git a/direnvrc b/direnvrc
index 33c5c32..754bbc8 100644
--- a/direnvrc
+++ b/direnvrc
@@ -249,7 +249,14 @@ use_nix() {
   local attribute=
   local packages=""
   local extra_args=()
+
   local nixfile=
+  if [[ -e "shell.nix" ]]; then
+    nixfile="./shell.nix"
+  elif [[ -e "default.nix" ]]; then
+    nixfile="./default.nix"
+  fi
+
   while [[ "$#" -gt 0 ]]; do
     i="$1"
     shift
@@ -295,7 +302,9 @@ use_nix() {
     esac
   done
 
-  nix_direnv_watch_file "$HOME/.direnvrc" "$HOME/.config/direnv/direnvrc" .envrc default.nix shell.nix
+  # nixfile may be empty,
+  # but nix_direnv_watch_file checks for existance before adding to watches
+  nix_direnv_watch_file "$HOME/.direnvrc" "$HOME/.config/direnv/direnvrc" .envrc "$nixfile"
 
   local need_update=0
   local file=
@@ -317,15 +326,6 @@ use_nix() {
     if [[ "$packages" != "" ]]; then
       extra_args+=("--expr" "with import <nixpkgs> {}; mkShell { buildInputs = [ $packages ]; }")
     else
-      # figure out what file we should use
-      if [[ "$nixfile" == "" ]]; then
-        if [[ -e "shell.nix" ]]; then
-          nixfile="./shell.nix"
-        elif [[ -e "default.nix" ]]; then
-          nixfile="./default.nix"
-        fi
-      fi
-
       # figure out what attribute we should build
       if [[ "$attribute" == "" ]]; then
         extra_args+=("--file" "$nixfile")