diff --git a/install.sh b/install.sh
index c323ede..ec90d38 100755
--- a/install.sh
+++ b/install.sh
@@ -84,7 +84,7 @@ discover_services() {
 			DISCOVERY_DIR="/usr/local/bin/"
 		else
 			# while not an absolute path
-			while [ ${DISCOVERY_DIR:0:1} != "/" ]; do
+			while [ "${DISCOVERY_DIR:0:1}" != "/" ]; do
 				echo "The path must be absolute, for example /usr/local/bin/. Please type it again."
 				read -r DISCOVERY_DIR;
 			done