diff --git a/start-kafka-manager.sh b/start-kafka-manager.sh
index 92e9d47..9dae12f 100644
--- a/start-kafka-manager.sh
+++ b/start-kafka-manager.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if [[ $KM_USERNAME != ''  && $KM_PASSWORD != '' ]]; then
+if [ "x$KM_USERNAME" != "x" ] && [ "x$KM_PASSWORD" != "x" ]; then
     sed -i.bak '/^basicAuthentication/d' /kafka-manager-${KM_VERSION}/conf/application.conf
     echo 'basicAuthentication.enabled=true' >> /kafka-manager-${KM_VERSION}/conf/application.conf
     echo "basicAuthentication.username=${KM_USERNAME}" >> /kafka-manager-${KM_VERSION}/conf/application.conf
@@ -8,4 +8,4 @@ if [[ $KM_USERNAME != ''  && $KM_PASSWORD != '' ]]; then
     echo 'basicAuthentication.realm="Kafka-Manager"' >> /kafka-manager-${KM_VERSION}/conf/application.conf
 fi
 
-exec ./bin/kafka-manager -Dconfig.file=${KM_CONFIGFILE} "${KM_ARGS}" "${@}"
\ No newline at end of file
+exec ./bin/kafka-manager -Dconfig.file=${KM_CONFIGFILE} "${KM_ARGS}" "${@}"