diff --git a/nse_main.cc b/nse_main.cc
index 4a2f43a3d..d10177931 100644
--- a/nse_main.cc
+++ b/nse_main.cc
@@ -1,11 +1,5 @@
 #include "nse_main.h"
 
-extern "C" {
-	#include "lua.h"
-	#include "lualib.h"
-	#include "lauxlib.h"
-}
-
 #include "nse_init.h"
 #include "nse_nsock.h"
 #include "nse_nmaplib.h"
diff --git a/nse_main.h b/nse_main.h
index 00390525a..8b0247c8d 100644
--- a/nse_main.h
+++ b/nse_main.h
@@ -1,6 +1,12 @@
 #ifndef NMAP_LUA_H
 #define NMAP_LUA_H
 
+extern "C" {
+  #include "lua.h"
+  #include "lualib.h"
+  #include "lauxlib.h"
+}
+
 #include <vector>
 #include <list>
 #include <string>
@@ -20,5 +26,7 @@ int script_updatedb();
 
 //parses the arguments provided to scripts via nmap's --script-args option 
 int script_check_args();
+
+int process_waiting2running(lua_State *, int);
 #endif
 
diff --git a/nse_nmaplib.cc b/nse_nmaplib.cc
index df71cc5f7..52dddb787 100644
--- a/nse_nmaplib.cc
+++ b/nse_nmaplib.cc
@@ -2,6 +2,7 @@
 #include "nse_nsock.h"
 #include "nse_macros.h"
 #include "nse_debug.h"
+#include "nse_main.h"
 
 #include "nmap.h"
 #include "nmap_error.h"
@@ -45,6 +46,72 @@ static int l_get_timing_level(lua_State *L);
 
 int l_clock_ms(lua_State *L);
 
+static int mutex_i;
+
+static int aux_mutex (lua_State *L)
+{
+  static const char * op[] = {"lock", "done", "trylock", "running", NULL};
+  switch (luaL_checkoption(L, 1, NULL, op))
+  {
+    case 0: // lock
+      if (lua_isnil(L, lua_upvalueindex(2))) // check running
+      {
+        lua_pushthread(L);
+        lua_replace(L, lua_upvalueindex(2)); // set running
+        return 0;
+      }
+      lua_pushthread(L);
+      lua_rawseti(L, lua_upvalueindex(1), lua_objlen(L, lua_upvalueindex(1))+1);
+      return lua_yield(L, 0);
+    case 1: // done
+      lua_pushthread(L);
+      if (!lua_equal(L, -1, lua_upvalueindex(2)))
+        luaL_error(L, "%s", "Do not have a lock on this mutex");
+      lua_getfield(L, LUA_REGISTRYINDEX, "table.remove");
+      lua_pushvalue(L, lua_upvalueindex(1));
+      lua_pushinteger(L, 1);
+      lua_call(L, 2, 1);
+      lua_replace(L, lua_upvalueindex(2));
+      if (!lua_isnil(L, lua_upvalueindex(2))) // waiting threads had a thread
+        process_waiting2running(lua_tothread(L, lua_upvalueindex(2)), 0);
+      return 0;
+    case 2: // trylock
+      if (lua_isnil(L, lua_upvalueindex(2)))
+      {
+        lua_pushthread(L);
+        lua_replace(L, lua_upvalueindex(2));
+        lua_pushboolean(L, true);
+      }
+      else
+        lua_pushboolean(L, false);
+      return 1;
+    case 3: // running
+      lua_pushvalue(L, lua_upvalueindex(2));
+      return 1;
+  }
+  return 0;
+}
+
+static int l_mutex (lua_State *L)
+{
+  int t = lua_type(L, 1);
+  if (t == LUA_TNONE || t == LUA_TNIL || t == LUA_TBOOLEAN || t == LUA_TNUMBER)
+    luaL_argerror(L, 1, "Object expected");
+  lua_rawgeti(L, LUA_REGISTRYINDEX, mutex_i);
+  lua_pushvalue(L, 1);
+  lua_gettable(L, -2);
+  if (lua_isnil(L, -1))
+  {
+    lua_newtable(L); // waiting threads
+    lua_pushnil(L); // running thread
+    lua_pushcclosure(L, aux_mutex, 2);
+    lua_pushvalue(L, 1); // "mutex object"
+    lua_pushvalue(L, -2); // function
+    lua_settable(L, -5); // Add to mutex table
+  }
+  return 1; // aux_mutex closure
+}
+
 int luaopen_nmap (lua_State *L)
 {
   static luaL_reg nmaplib [] = {
@@ -62,6 +129,7 @@ int luaopen_nmap (lua_State *L)
     {"have_ssl", l_get_have_ssl},
     {"fetchfile", l_fetchfile},
     {"timing_level", l_get_timing_level},
+    {"mutex", l_mutex},
     {NULL, NULL} 
   };
 
@@ -70,6 +138,13 @@ int luaopen_nmap (lua_State *L)
   lua_newtable(L);
   lua_setfield(L, -2, "registry");
 
+  lua_newtable(L);
+  lua_createtable(L, 0, 1);
+  lua_pushliteral(L, "v");
+  lua_setfield(L, -2, "__mode");
+  lua_setmetatable(L, -2); // Allow closures to be collected (see l_mutex)
+  mutex_i = luaL_ref(L, LUA_REGISTRYINDEX);
+
   SCRIPT_ENGINE_TRY(l_nsock_open(L));
   SCRIPT_ENGINE_TRY(l_dnet_open(L));