diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index 595ebc9..8e61cbb 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -33,6 +33,7 @@ setopt NO_UNSET WARN_CREATE_GLOBAL
 
 local -r root=${0:h:h}
 
+(){
 # Check an highlighter was given as argument.
 [[ -n "$1" ]] || {
   echo >&2 "Bail out! You must provide the name of a valid highlighter as argument."
@@ -219,3 +220,4 @@ for data_file in $root/highlighters/$1/test-data/*.zsh; do
 done
 
 exit $something_failed
+} "$@"