diff --git a/lib/console-text-color-themes.sh b/lib/console-text-color-themes.sh
index c7b3d287..4f9b4fb9 100755
--- a/lib/console-text-color-themes.sh
+++ b/lib/console-text-color-themes.sh
@@ -26,10 +26,6 @@ if command -v greadlink >/dev/null; then
   _ctct_READLINK_CMD=greadlink
 fi
 
-# NOTE: DO NOT declare var _ctct_PROG as readonly in ONE line!
-_ctct_PROG="$(basename -- "$($_ctct_READLINK_CMD -f -- "${BASH_SOURCE[0]}")")"
-[ "$_ctct_PROG" == 'console-text-color-themes.sh' ] && readonly _ctct_is_direct_run=true
-
 readonly _ctct_ec=$'\033'      # escape char
 readonly _ctct_eend=$'\033[0m' # escape end
 
@@ -55,9 +51,10 @@ colorEchoWithoutNewLine() {
   fi
 }
 
-# if not directly run this script(use as lib), just export 2 helper functions,
-# and do NOT print anything.
-[ "$_ctct_is_direct_run" == true ] && {
+# if not directly run this script(use as lib), just export 2 helper functions, and do NOT print anything.
+#
+# if directly run this script, the length of array BASH_SOURCE is 1.
+if ((${#BASH_SOURCE[@]} == 1)); then
   for style in 0 1 2 3 4 5 6 7; do
     for fg in 30 31 32 33 34 35 36 37; do
       for bg in 40 41 42 43 44 45 46 47; do
@@ -97,4 +94,4 @@ colorEchoWithoutNewLine() {
   echo 'Output of above code:'
   echo -n '    '
   colorEcho '1;36;41' 'Sample Text'
-}
+fi