diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 588ebe6..58da522 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -8,6 +8,7 @@ bug reports and code to this ntp docker project:
  - Gontier-Julien      => https://github.com/Gontier-Julien
  - Guru Govindan       => https://github.com/ggovindan
  - Kim Oliver Drechsel => https://github.com/kimdre
+ - Mingye Wang         => https://github.com/Artoria2e5
  - Nicolas Carrier     => https://github.com/ncarrier
  - Nicolas Innocenti   => https://github.com/nicoinn
  - Richard Coleman     => https://github.com/microbug
diff --git a/assets/startup.sh b/assets/startup.sh
index 04e33e5..e3b7135 100755
--- a/assets/startup.sh
+++ b/assets/startup.sh
@@ -38,7 +38,7 @@ if [ -z "${LOG_LEVEL}" ]; then
   LOG_LEVEL=0
 else
   # confirm log level is between 0-3, since these are the only log levels supported
-  if [ "${LOG_LEVEL}" -gt 3 ]; then
+  if expr "${LOG_LEVEL}" : [^0123] > /dev/null; then
     # level outside of supported range, let's set to default (0)
     LOG_LEVEL=0
   fi
@@ -52,15 +52,15 @@ for N in $NTP_SERVERS; do
   # check if ntp server has a 127.0.0.0/8 address (RFC3330) indicating it's
   # the local system clock
   if [[ "${N_CLEANED}" == "127\."* ]]; then
-    echo "server "${N_CLEANED} >> ${CHRONY_CONF_FILE}
+    echo "server ${N_CLEANED}" >> ${CHRONY_CONF_FILE}
     echo "local stratum 10"    >> ${CHRONY_CONF_FILE}
 
   # found external time servers
   else
     if [[ "${ENABLE_NTS:-false}" = true ]]; then
-      echo "server "${N_CLEANED}" iburst nts" >> ${CHRONY_CONF_FILE}
+      echo "server ${N_CLEANED} iburst nts" >> ${CHRONY_CONF_FILE}
     else
-      echo "server "${N_CLEANED}" iburst" >> ${CHRONY_CONF_FILE}
+      echo "server ${N_CLEANED} iburst" >> ${CHRONY_CONF_FILE}
     fi
   fi
 done