diff --git a/navi b/navi
index 3288efad..d58d2c03 100755
--- a/navi
+++ b/navi
@@ -4,7 +4,7 @@ set -euo pipefail
 export NAVI_HOME="$(cd "$(dirname "$0")" && pwd)"
 source "${NAVI_HOME}/src/main.sh"
 
-VERSION="0.16.0"
+VERSION="0.17.0"
 NAVI_ENV="${NAVI_ENV:-prod}"
 
 opts::eval "$@"
diff --git a/src/ui.sh b/src/ui.sh
index 388d3d9a..6716c759 100644
--- a/src/ui.sh
+++ b/src/ui.sh
@@ -20,7 +20,7 @@ ui::fzf() {
 ui::select() {
    local -r cheats="$1"
 
-   [[ "$SHELL" =~ 'fish' ]] || local -r sub='$'
+   [[ "${SHELL:-}" =~ 'fish' ]] || local -r sub='$'
 
    local -r script_path="${NAVI_HOME}/navi"
    local -r preview_cmd="\"${script_path}\" preview ${sub:-}(echo \'{}\' | $(arg::serialize_code))"
@@ -95,4 +95,4 @@ ui::print_preview() {
    printf " \033[${tag_color}m["; echo -n "$tags"; echo "]"
    printf "\033[${snippet_color}m"
    echo "$snippet" | ui::remove_dep_order
-}
\ No newline at end of file
+}