diff --git a/wled b/wled
index c6e28d4..00b1fe8 100755
--- a/wled
+++ b/wled
@@ -10,6 +10,9 @@ NAME="wled.sh"
 COMMAND="wled"
 VERSION="0.1.3"
 
+exit_code=0
+host_list=
+
 # Make the exit status of command pipelines the status of the last command
 # with non-zero exit status - if supported by this shell.
 (set -o pipefail 2>/dev/null) && set -o pipefail
@@ -67,44 +70,39 @@ current_brightness() {
         sed -n 's/.*"state"[[:space:]]*:[[:space:]]*{[^}]*"bri"[[:space:]]*:[[:space:]]*\([0-9]\{1,3\}\).*/\1/p'
 }
 
-arg_inst="$1"
-arg_cmnd="$2"
-arg_param="$3"
-exit_code=0
-
-# Clear positional arguments.
-set --
-
-# Parse instance argument and store hostnames as positional arguments.
-case "$arg_inst" in
-    ""|-h|--help) # Missing instance parameter.
-        print_help
-        exit 0
-    ;;
-    -v|--version)
-        echo "$NAME version $VERSION"
-        exit 0
-    ;;
-    -a|--all)
-        set -- 'wled-fnordcenter.local' \
-               'wled-wohnzimmer.local'
-    ;;
-    -f|--fnordcenter)
-        set -- 'wled-fnordcenter.local'
-    ;;
-    -w|--wohnzimmer)
-        set -- 'wled-wohnzimmer.local'
-    ;;
-    *) # Unknown instance parameter.
-        echo "Error: unknown instance \"$arg_inst\"." >&2
-        print_usage
-        exit 1
-    ;;
-esac
+# Parse instance argument and store hostnames.
+while test $# -gt 0; do
+    case "$1" in
+        ""|-h|--help) # Missing instance parameter.
+            print_help
+            exit 0
+        ;;
+        -v|--version)
+            echo "$NAME version $VERSION"
+            exit 0
+        ;;
+        -a|--all)
+            host_list="wled-fnordcenter.local wled-wohnzimmer.local"
+        ;;
+        -f|--fnordcenter)
+            host_list="$host_list wled-fnordcenter.local"
+        ;;
+        -w|--wohnzimmer)
+            host_list="$host_list wled-wohnzimmer.local"
+        ;;
+        *) # Unknown instance parameter.
+            test -n "$host_list" && break
+            echo "Error: not a valid instance option (\"$1\")." >&2
+            print_usage
+            exit 1
+        ;;
+    esac
+    shift
+done
 
 # Parse and execute command argument against given instances.
-for wled_host; do
-    case "$arg_cmnd" in
+for wled_host in $host_list; do
+    case "$1" in
         on) # Switch on.
             api_resp=$(curl_send '{"on":true}' "http://$wled_host/json")
         ;;
@@ -112,13 +110,13 @@ for wled_host; do
             api_resp=$(curl_send '{"on":false}' "http://$wled_host/json")
         ;;
         -b|--brightness) # Set brightness.
-            if test -z "$arg_param"; then
+            if test -z "$2"; then
                 # No parameter given. Print current brightness.
                 echo "Brightness of $wled_host:"
                 current_brightness "$wled_host"
             else
                 # Try to convert 3rd parameter to an integer between 1 an 255.
-                bright=$(printf '%u' "$arg_param" 2>/dev/null)
+                bright=$(printf '%u' "$2" 2>/dev/null)
                 if test $? -gt 0; then # Conversion failed.
                     echo "Error: unable to parse parameter for brightness." >&2
                     exit 1
@@ -130,7 +128,7 @@ for wled_host; do
             fi
         ;;
         [1-9]|1[0-7]) # Switch to preset.
-            api_resp=$(curl_send "{'ps':$arg_cmnd}" "http://$wled_host/json")
+            api_resp=$(curl_send "{'ps':$1}" "http://$wled_host/json")
         ;;
         l|list) # List presets.
             printf "loading ...\r"
@@ -164,7 +162,7 @@ for wled_host; do
             exit 1
         ;;
         *) # Unknown command.
-            echo "Error: unknown command \"$arg_cmnd\"." >&2
+            echo "Error: unknown command \"$1\"." >&2
             print_usage
             exit 1
         ;;