diff --git a/install-nix.sh b/install-nix.sh
index 03447c3..7d9a6ef 100755
--- a/install-nix.sh
+++ b/install-nix.sh
@@ -1,8 +1,8 @@
 #!/usr/bin/env bash
 set -euo pipefail
 
-if type -p nix &>/dev/null ; then
-  echo "Aborting: Nix is already installed at $(type -p nix)"
+if nix_path="$(type -p nix)" ; then
+  echo "Aborting: Nix is already installed at ${nix_path}"
   exit
 fi
 
@@ -15,7 +15,7 @@ trap 'rm -rf "$workdir"' EXIT
 
 # Configure Nix
 add_config() {
-  echo "$1" | tee -a "$workdir/nix.conf" >/dev/null
+  echo "$1" >> "$workdir/nix.conf"
 }
 # Set jobs to number of cores
 add_config "max-jobs = auto"
@@ -28,7 +28,7 @@ elif [[ -n "${GITHUB_TOKEN:-}" ]]; then
   add_config "access-tokens = github.com=$GITHUB_TOKEN"
 fi
 # Append extra nix configuration if provided
-if [[ $INPUT_EXTRA_NIX_CONFIG != "" ]]; then
+if [[ -n "${INPUT_EXTRA_NIX_CONFIG:-}" ]]; then
   add_config "$INPUT_EXTRA_NIX_CONFIG"
 fi
 if [[ ! $INPUT_EXTRA_NIX_CONFIG =~ "experimental-features" ]]; then
@@ -54,10 +54,10 @@ else
   add_config "build-users-group ="
   sudo mkdir -p /etc/nix
   sudo chmod 0755 /etc/nix
-  sudo cp $workdir/nix.conf /etc/nix/nix.conf
+  sudo cp "$workdir/nix.conf" /etc/nix/nix.conf
 fi
 
-if [[ $INPUT_INSTALL_OPTIONS != "" ]]; then
+if [[ -n "${INPUT_INSTALL_OPTIONS:-}" ]]; then
   IFS=' ' read -r -a extra_installer_options <<< "$INPUT_INSTALL_OPTIONS"
   installer_options=("${extra_installer_options[@]}" "${installer_options[@]}")
 fi
@@ -91,7 +91,7 @@ echo "/nix/var/nix/profiles/default/bin" >> "$GITHUB_PATH"
 # new path for nix 2.14
 echo "$HOME/.nix-profile/bin" >> "$GITHUB_PATH"
 
-if [[ $INPUT_NIX_PATH != "" ]]; then
+if [[ -n "${INPUT_NIX_PATH:-}" ]]; then
   echo "NIX_PATH=${INPUT_NIX_PATH}" >> "$GITHUB_ENV"
 fi