diff --git a/bashttpd b/bashttpd
index 9ed8d21..b632070 100755
--- a/bashttpd
+++ b/bashttpd
@@ -6,10 +6,11 @@
 #
 # Original author: Avleen Vig, 2012
 # Reworked by:     Josh Cartwright, 2012
+# QA:              Jacob Hrbek, 2019
 
-warn() { echo "WARNING: $@" >&2; }
+warn() { printf 'WARNING %s\n' "$@" >&2; }
 
-[ -r bashttpd.conf ] || {
+[ ! -e bashttpd.conf ] && {
    cat >bashttpd.conf <<'EOF'
 #
 # bashttpd.conf - configuration for bashttpd
@@ -104,13 +105,15 @@ EOF
    exit 1
 }
 
-recv() { echo "< $@" >&2; }
-send() { echo "> $@" >&2;
-         printf '%s\r\n' "$*"; }
+recv() { printf "< %s\n" "$@" >&2; }
+send() {
+  printf "> %s\n" "$@" >&2
+  printf '%s\r\n' "$*"
+}
 
-[[ $UID = 0 ]] && warn "It is not recommended to run bashttpd as root."
+[ -z "$(id -u)" ] && warn "It is not recommended to run bashttpd as root."
 
-DATE=$(date +"%a, %d %b %Y %H:%M:%S %Z")
+DATE="$(date +"%a, %d %b %Y %H:%M:%S %Z")"
 declare -a RESPONSE_HEADERS=(
       "Date: $DATE"
    "Expires: $DATE"
@@ -131,7 +134,7 @@ declare -a HTTP_RESPONSE=(
 )
 
 send_response() {
-   local code=$1
+   local code="$1"
    send "HTTP/1.0 $1 ${HTTP_RESPONSE[$1]}"
    for i in "${RESPONSE_HEADERS[@]}"; do
       send "$i"
@@ -150,9 +153,9 @@ fail_with() {
 }
 
 serve_file() {
-   local file=$1
+   local file="$1"
 
-   CONTENT_TYPE=
+   CONTENT_TYPE=""
    case "$file" in
      *\.css)
        CONTENT_TYPE="text/css"
@@ -180,7 +183,7 @@ serve_dir_with_tree()
    add_response_header "Content-Type" "text/html"
 
    # The --du option was added in 1.6.0.
-   read x tree_vers x < <(tree --version)
+   read -r x tree_vers x < <(tree --version)
    [[ $tree_vers == v1.6* ]] && tree_opts="--du"
 
    send_response_ok_exit < \
@@ -189,7 +192,7 @@ serve_dir_with_tree()
 
 serve_dir_with_ls()
 {
-   local dir=$1
+   local dir="$1"
 
    add_response_header "Content-Type" "text/plain"
 
@@ -198,7 +201,7 @@ serve_dir_with_ls()
 }
 
 serve_dir() {
-   local dir=$1
+   local dir="$1"
 
    # If `tree` is installed, use that for pretty output.
    which tree &>/dev/null && \
@@ -210,22 +213,22 @@ serve_dir() {
 }
 
 serve_dir_or_file_from() {
-   local URL_PATH=$1/$3
+   local URL_PATH="$1/$3"
    shift
 
    # sanitize URL_PATH
-   URL_PATH=${URL_PATH//[^a-zA-Z0-9_~\-\.\/]/}
-   [[ $URL_PATH == *..* ]] && fail_with 400
+   URL_PATH="${URL_PATH//[^a-zA-Z0-9_~\-\.\/]/}"
+   [[ "$URL_PATH" == *..* ]] && fail_with 400
 
    # Serve index file if exists in requested directory
-   [[ -d $URL_PATH && -f $URL_PATH/index.html && -r $URL_PATH/index.html ]] && \
+   [ -d "$URL_PATH" ] && [ -f "$URL_PATH/index.html" ] && [ -r "$URL_PATH/index.html" ] && \
       URL_PATH="$URL_PATH/index.html"
 
-   if [[ -f $URL_PATH ]]; then
-      [[ -r $URL_PATH ]] && \
+   if [ -f "$URL_PATH" ]; then
+      [ -r "$URL_PATH" ] && \
          serve_file "$URL_PATH" "$@" || fail_with 403
-   elif [[ -d $URL_PATH ]]; then
-      [[ -x $URL_PATH ]] && \
+   elif [ -d "$URL_PATH" ]; then
+      [ -x "$URL_PATH" ] && \
          serve_dir  "$URL_PATH" "$@" || fail_with 403
    fi
 
@@ -238,10 +241,10 @@ serve_static_string() {
 }
 
 on_uri_match() {
-   local regex=$1
+   local regex="$1"
    shift
 
-   [[ $REQUEST_URI =~ $regex ]] && \
+   [[ "$REQUEST_URI" =~ $regex ]] && \
       "$@" "${BASH_REMATCH[@]}"
 }
 
@@ -253,7 +256,7 @@ unconditionally() {
 read -r line || fail_with 400
 
 # strip trailing CR if it exists
-line=${line%%$'\r'}
+line="${line%%$'\r'}"
 recv "$line"
 
 read -r REQUEST_METHOD REQUEST_URI REQUEST_HTTP_VERSION <<<"$line"
@@ -269,7 +272,7 @@ read -r REQUEST_METHOD REQUEST_URI REQUEST_HTTP_VERSION <<<"$line"
 declare -a REQUEST_HEADERS
 
 while read -r line; do
-   line=${line%%$'\r'}
+   line="${line%%$'\r'}"
    recv "$line"
 
    # If we've reached the end of the headers, break.