diff --git a/CHANGELOG b/CHANGELOG
index a98b31eed..2622f0062 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,9 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE][GH#627] Fixed script hang in several brute scripts due to the "threads"
+  script-arg not being converted to a number. Error message was
+  "nselib/brute.lua:1188: attempt to compare number with string" [Arne Beer]
+
 Nmap 7.40 [2016-12-20]
 
 o [Windows] Updated the bundled Npcap from 0.10r9 to 0.78r5, with an
diff --git a/scripts/http-joomla-brute.nse b/scripts/http-joomla-brute.nse
index 988e77e63..d47d8ff94 100644
--- a/scripts/http-joomla-brute.nse
+++ b/scripts/http-joomla-brute.nse
@@ -137,7 +137,7 @@ action = function( host, port )
   local status, result, engine
   local uservar = stdnse.get_script_args('http-joomla-brute.uservar') or DEFAULT_JOOMLA_USERVAR
   local passvar = stdnse.get_script_args('http-joomla-brute.passvar') or DEFAULT_JOOMLA_PASSVAR
-  local thread_num = stdnse.get_script_args("http-joomla-brute.threads") or DEFAULT_THREAD_NUM
+  local thread_num = tonumber(stdnse.get_script_args("http-joomla-brute.threads")) or DEFAULT_THREAD_NUM
 
   engine = brute.Engine:new( Driver, host, port, { uservar = uservar, passvar = passvar } )
   engine:setMaxThreads(thread_num)
diff --git a/scripts/http-wordpress-brute.nse b/scripts/http-wordpress-brute.nse
index 85f739482..41376ad25 100644
--- a/scripts/http-wordpress-brute.nse
+++ b/scripts/http-wordpress-brute.nse
@@ -131,7 +131,7 @@ action = function( host, port )
   local status, result, engine
   local uservar = stdnse.get_script_args('http-wordpress-brute.uservar') or DEFAULT_WP_USERVAR
   local passvar = stdnse.get_script_args('http-wordpress-brute.passvar') or DEFAULT_WP_PASSVAR
-  local thread_num = stdnse.get_script_args("http-wordpress-brute.threads") or DEFAULT_THREAD_NUM
+  local thread_num = tonumber(stdnse.get_script_args("http-wordpress-brute.threads")) or DEFAULT_THREAD_NUM
 
   engine = brute.Engine:new( Driver, host, port, { uservar = uservar, passvar = passvar } )
   engine:setMaxThreads(thread_num)
diff --git a/scripts/mikrotik-routeros-brute.nse b/scripts/mikrotik-routeros-brute.nse
index 2be98da14..0431b0eb8 100644
--- a/scripts/mikrotik-routeros-brute.nse
+++ b/scripts/mikrotik-routeros-brute.nse
@@ -90,7 +90,7 @@ Driver =
 }
 
 action = function(host, port)
-  local thread_num = stdnse.get_script_args(SCRIPT_NAME..".threads") or 1
+  local thread_num = tonumber(stdnse.get_script_args(SCRIPT_NAME..".threads")) or 1
   local options = {timeout = 5000}
   local bengine = brute.Engine:new(Driver, host, port, options)
 
diff --git a/scripts/nessus-xmlrpc-brute.nse b/scripts/nessus-xmlrpc-brute.nse
index 3c428cbbf..c62e4e14a 100644
--- a/scripts/nessus-xmlrpc-brute.nse
+++ b/scripts/nessus-xmlrpc-brute.nse
@@ -33,7 +33,7 @@ portrule = shortport.port_or_service(8834, "ssl/http", "tcp")
 
 local arg_timeout = stdnse.parse_timespec(stdnse.get_script_args(SCRIPT_NAME..'.timeout'))
 arg_timeout = (arg_timeout or 5) * 1000
-local arg_threads = stdnse.get_script_args("nessus-xmlrpc-brute.threads")
+local arg_threads = tonumber(stdnse.get_script_args("nessus-xmlrpc-brute.threads"))
 
 local function authenticate(host, port, username, password)
   local post_data = ("login=%s&password=%s"):format(username, password)