diff --git a/bin/miaou-bash b/bin/miaou-bash
index 1bbc137..3062b6b 100755
--- a/bin/miaou-bash
+++ b/bin/miaou-bash
@@ -8,6 +8,10 @@ readonly MIAOU_BASH_ERROR MIAOU_BASH_DEBUG
 
 # FUNCTIONS
 
+function is_true {
+  [[ "${1,,}" =~ ^(true|yes|1)$ ]]
+}
+
 # overridden function which permits backtracing of original `return` statement
 function false {
   >&2 echo "${BASH_SOURCE[1]}:${BASH_LINENO[0]} false"
@@ -178,8 +182,7 @@ function on_exit {
 }
 
 function debug {
-  [[ "${MIAOU_BASH_DEBUG}" == true ]] && >/dev/tty echo "*********** DEBUG: $*" ||
-    true
+  is_true "${MIAOU_BASH_DEBUG}" && >/dev/tty echo "*********** DEBUG: $*" || true
 }
 
 function dump_failure {
@@ -206,9 +209,9 @@ function dump_failure {
 function dump_stderr {
   last_trim=${1:-false}
   mapfile -t tmp_error <"$MIAOU_BASH_ERROR"
-  $last_trim && unset 'tmp_error[-1]' && tmp_error=("${tmp_error[@]}")
+  is_true "$last_trim" && unset 'tmp_error[-1]' && tmp_error=("${tmp_error[@]}")
   if [[ "${#tmp_error[@]}" -gt 0 ]]; then
-    $MIAOU_BASH_DEBUG && >/dev/tty echo '---stderr---'
+    debug '---stderr---'
     for i in "${tmp_error[@]}"; do
       >&4 echo -e "$i"
     done
diff --git a/test/miaou-bash.test.bash b/test/miaou-bash.test.bash
index 5b36257..65b1c8d 100755
--- a/test/miaou-bash.test.bash
+++ b/test/miaou-bash.test.bash
@@ -1,3 +1,6 @@
 #!/usr/bin/env bash
+# do not use miaou-bash as the shebang
 
+./test/stub/scenario.bash success >/dev/null
 [[ $(./test/stub/scenario.bash unbound_variable 2>&1 1>/dev/null) =~ 'TYPE: UNBOUND VARIABLE' ]]
+[[ $(./test/stub/scenario.bash false 2>&1 1>/dev/null) =~ 'TYPE: FALSE' ]]
diff --git a/test/stub/scenario.bash b/test/stub/scenario.bash
index 4117235..526218b 100755
--- a/test/stub/scenario.bash
+++ b/test/stub/scenario.bash
@@ -30,7 +30,7 @@ function do_success {
   source "${MIAOU_BASH_DIR}/lib/ansi.bash"
   local content
   content=$(PADDING_LEFT=2 PADDING_RIGHT=6 style_padding 'this is success')
-  content=$(FG=PURPLE BG=GRAY style_ansi "$content")
+  content=$(FG=YELLOW BG=BLUE style_ansi "$content")
   FG=BLACK BG=RED PADDING=8 style_block "$content"
 }