diff --git a/include/lua.h b/include/lua.h
index 5248f72..769d472 100644
--- a/include/lua.h
+++ b/include/lua.h
@@ -262,6 +262,7 @@ LUA_API void  (lua_halt) (lua_State *L); /* forcefully halts the Lua state speci
 											warning: this will leave the state in an invalid state;
 											do not use the state after calling this - close it immediately */
 LUA_API void  (lua_externalerror) (lua_State *L, const char * message); /* throws an error into a running state - meant to be run from a different thread */
+LUA_API void  (lua_setlockstate) (lua_State *L, int enabled); /* enables/disables lua_lock */
 
 
 
diff --git a/src/lapi.c b/src/lapi.c
index d9db268..39bf61b 100644
--- a/src/lapi.c
+++ b/src/lapi.c
@@ -1166,3 +1166,13 @@ LUA_API void lua_externalerror(lua_State *L, const char * message) {
   lua_unlock(L);
 }
 
+LUA_API void lua_setlockstate(lua_State *L, int enabled) {
+  lua_lock(L);
+  if (!enabled) {
+    G(L)->lockstate = G(L)->lockstate >= 2 ? 2 : 3;
+  } else {
+    G(L)->lockstate = G(L)->lockstate >= 2 ? 0 : 1;
+  }
+  lua_unlock(L);
+}
+
diff --git a/src/lcode.c b/src/lcode.c
index 3bdfd63..ce9f6e5 100644
--- a/src/lcode.c
+++ b/src/lcode.c
@@ -626,7 +626,8 @@ void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
 
 static lua_Number luai_nummod(lua_Number a, lua_Number b) {
   lua_Number q = fmod(a, b);
-  if ((a < 0) != (b < 0) && q != 0) return q + b;
+  if (q == 0) return 0;
+  else if ((a < 0) != (b < 0)) return q + b;
   return q;
 }
 
diff --git a/src/llock.cpp b/src/llock.cpp
index 0c215a4..18c6f93 100644
--- a/src/llock.cpp
+++ b/src/llock.cpp
@@ -8,16 +8,17 @@ extern "C" {
 
 extern "C" {
     void _lua_lock(lua_State *L) {
+        if (G(L)->lockstate == 2) return;
         ((std::mutex*)G(L)->lock)->lock();
         G(L)->lockstate = 1;
     }
 
     void _lua_unlock(lua_State *L) {
-        if (!G(L)->lockstate) {
+        if (G(L)->lockstate != 1 && G(L)->lockstate != 3) {
             //fprintf(stderr, "Attempted to unlock a thread twice!\n");
             return;
         }
-        G(L)->lockstate = 0;
+        G(L)->lockstate--;
         ((std::mutex*)G(L)->lock)->unlock();
     }
 
diff --git a/src/lua.h b/src/lua.h
index d77f31a..8759ada 100644
--- a/src/lua.h
+++ b/src/lua.h
@@ -262,6 +262,7 @@ LUA_API void  (lua_halt) (lua_State *L); /* forcefully halts the Lua state speci
 											warning: this will leave the state in an invalid state;
 											do not use the state after calling this - close it immediately */
 LUA_API void  (lua_externalerror) (lua_State *L, const char * message); /* throws an error into a running state - meant to be run from a different thread */
+LUA_API void  (lua_setlockstate) (lua_State *L, int enabled); /* enables/disables lua_lock */
 
 
 /* 
diff --git a/src/lvm.c b/src/lvm.c
index 517bb3a..bc3e3d6 100644
--- a/src/lvm.c
+++ b/src/lvm.c
@@ -319,7 +319,8 @@ void luaV_concat (lua_State *L, int total, int last) {
 
 static lua_Number luai_nummod(lua_Number a, lua_Number b) {
   lua_Number q = fmod(a, b);
-  if ((a < 0) != (b < 0) && q != 0) return q + b;
+  if (q == 0) return 0;
+  else if ((a < 0) != (b < 0)) return q + b;
   return q;
 }