diff --git a/utils/lib_utils.sh b/utils/lib_utils.sh
index cc7594e..6e3cb87 100644
--- a/utils/lib_utils.sh
+++ b/utils/lib_utils.sh
@@ -44,13 +44,13 @@ set -o nounset                              # Treat unset variables as an error
 function make_working_dir { 
 
 	# the directory of the script
-	DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+	local DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 	# the temp directory used, within $DIR
 	# omit the -p parameter to create a temporal directory in 
 	# the default location
 	
-	WORK_DIR=`mktemp -d -p "$DIR"`
+	local WORK_DIR=`mktemp -d -p "$DIR"`
 
 	# check if tmp dir was created
 	if [[ ! "$WORK_DIR" || ! -d "$WORK_DIR" ]]; then