diff --git a/agent/agent.sh b/agent/agent.sh
index ec08abe..11f29fa 100644
--- a/agent/agent.sh
+++ b/agent/agent.sh
@@ -40,12 +40,12 @@ function downloadUpdate {
   remote_size=$(curl -sIk -m 4 "${URL}" | grep -i "content-length:" | tr -d " \t" | cut -d ':' -f 2)
   remote_size=${remote_size//$'\r'}
 
-  [ "$remote_size" == "" || "$remote_size" == "0" ] && return
+  [[ "$remote_size" == "" || "$remote_size" == "0" ]] && return
 
   SCRIPT=$(readlink -f ${BASH_SOURCE[0]})
   local_size=$(stat -c%s "$SCRIPT")
 
-  [ remote_size -eq local_size ] && return
+  [[ remote_size -eq local_size ]] && return
 
   if ! curl -sfk -m 10 -o "${TMP}" "${URL}"; then
     echo "$HEADER: curl error" && return