diff --git a/check_reversetunnel b/check_reversetunnel
index 7ce7b0a..8123394 100755
--- a/check_reversetunnel
+++ b/check_reversetunnel
@@ -12,7 +12,7 @@ if [ -z $AUTOSSH_PIDs ]; then
     exit $NAGIOS_ERROR
 else
     # there is an autossh process
-    ps x -q $AUTOSSH_PIDs | grep $MULTIMEDIA_TUNNEL_REGEX 2>&1 > /dev/null
+    ps x -q $AUTOSSH_PIDs | grep "$MULTIMEDIA_TUNNEL_REGEX" 2>&1 > /dev/null
     if [ $? -eq 0 ]; then
         echo "OK - The required autossh process is running"
         exit $NAGIOS_OK