diff --git a/lauxlib.c b/lauxlib.c
index 7cf90cb7..af44418a 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -874,7 +874,7 @@ LUALIB_API int luaL_loadbufferx (lua_State *L, const char *buff, size_t size,
 
 
 LUALIB_API int luaL_loadstring (lua_State *L, const char *s) {
-  return luaL_loadbuffer(L, s, strlen(s), s);
+  return luaL_loadbufferx(L, s, strlen(s), s, "t");
 }
 
 /* }====================================================== */
diff --git a/lbaselib.c b/lbaselib.c
index 891bb90f..47f7bdec 100644
--- a/lbaselib.c
+++ b/lbaselib.c
@@ -340,9 +340,11 @@ static int load_aux (lua_State *L, int status, int envidx) {
 
 
 static const char *getMode (lua_State *L, int idx) {
-  const char *mode = luaL_optstring(L, idx, "bt");
-  if (strchr(mode, 'B') != NULL)  /* Lua code cannot use fixed buffers */
+  const char *mode = luaL_optstring(L, idx, NULL);
+  if (mode != NULL && strchr(mode, 'B') != NULL) {
+    /* Lua code cannot use fixed buffers */
     luaL_argerror(L, idx, "invalid mode");
+  }
   return mode;
 }
 
@@ -425,7 +427,7 @@ static int dofilecont (lua_State *L, int d1, lua_KContext d2) {
 static int luaB_dofile (lua_State *L) {
   const char *fname = luaL_optstring(L, 1, NULL);
   lua_settop(L, 1);
-  if (l_unlikely(luaL_loadfile(L, fname) != LUA_OK))
+  if (l_unlikely(luaL_loadfilex(L, fname, "bt") != LUA_OK))
     return lua_error(L);
   lua_callk(L, 0, LUA_MULTRET, 0, dofilecont);
   return dofilecont(L, 0, 0);
diff --git a/ldblib.c b/ldblib.c
index c7b74812..051327cc 100644
--- a/ldblib.c
+++ b/ldblib.c
@@ -427,7 +427,7 @@ static int db_debug (lua_State *L) {
     if (fgets(buffer, sizeof(buffer), stdin) == NULL ||
         strcmp(buffer, "cont\n") == 0)
       return 0;
-    if (luaL_loadbuffer(L, buffer, strlen(buffer), "=(debug command)") ||
+    if (luaL_loadbufferx(L, buffer, strlen(buffer), "=(debug command)", "t") ||
         lua_pcall(L, 0, 0, 0))
       lua_writestringerror("%s\n", luaL_tolstring(L, -1, NULL));
     lua_settop(L, 0);  /* remove eventual returns */
diff --git a/loadlib.c b/loadlib.c
index 8d2e68e2..ef09c9a5 100644
--- a/loadlib.c
+++ b/loadlib.c
@@ -541,7 +541,7 @@ static int searcher_Lua (lua_State *L) {
   const char *name = luaL_checkstring(L, 1);
   filename = findfile(L, name, "path", LUA_LSUBSEP);
   if (filename == NULL) return 1;  /* module not found in this path */
-  return checkload(L, (luaL_loadfile(L, filename) == LUA_OK), filename);
+  return checkload(L, (luaL_loadfilex(L, filename, "bt") == LUA_OK), filename);
 }
 
 
diff --git a/ltests.c b/ltests.c
index ce2b20ca..6ae5f472 100644
--- a/ltests.c
+++ b/ltests.c
@@ -1302,7 +1302,7 @@ static int doonnewstack (lua_State *L) {
   lua_State *L1 = lua_newthread(L);
   size_t l;
   const char *s = luaL_checklstring(L, 1, &l);
-  int status = luaL_loadbuffer(L1, s, l, s);
+  int status = luaL_loadbufferx(L1, s, l, s, "t");
   if (status == LUA_OK)
     status = lua_pcall(L1, 0, 0, 0);
   lua_pushinteger(L, status);
@@ -1382,7 +1382,7 @@ static int doremote (lua_State *L) {
   const char *code = luaL_checklstring(L, 2, &lcode);
   int status;
   lua_settop(L1, 0);
-  status = luaL_loadbuffer(L1, code, lcode, code);
+  status = luaL_loadbufferx(L1, code, lcode, code, "t");
   if (status == LUA_OK)
     status = lua_pcall(L1, 0, LUA_MULTRET, 0);
   if (status != LUA_OK) {
@@ -1738,7 +1738,7 @@ static int runC (lua_State *L, lua_State *L1, const char *pc) {
       lua_pushinteger(L1, luaL_len(L1, getindex));
     }
     else if EQ("loadfile") {
-      luaL_loadfile(L1, luaL_checkstring(L1, getnum));
+      luaL_loadfilex(L1, luaL_checkstring(L1, getnum), "t");
     }
     else if EQ("loadstring") {
       size_t slen;
diff --git a/lua.c b/lua.c
index 3f4fc9f7..3107a674 100644
--- a/lua.c
+++ b/lua.c
@@ -207,12 +207,12 @@ static int dochunk (lua_State *L, int status) {
 
 
 static int dofile (lua_State *L, const char *name) {
-  return dochunk(L, luaL_loadfile(L, name));
+  return dochunk(L, luaL_loadfilex(L, name, "bt"));
 }
 
 
 static int dostring (lua_State *L, const char *s, const char *name) {
-  return dochunk(L, luaL_loadbuffer(L, s, strlen(s), name));
+  return dochunk(L, luaL_loadbufferx(L, s, strlen(s), name, "t"));
 }
 
 
@@ -266,7 +266,7 @@ static int handle_script (lua_State *L, char **argv) {
   const char *fname = argv[0];
   if (strcmp(fname, "-") == 0 && strcmp(argv[-1], "--") != 0)
     fname = NULL;  /* stdin */
-  status = luaL_loadfile(L, fname);
+  status = luaL_loadfilex(L, fname, "bt");
   if (status == LUA_OK) {
     int n = pushargs(L);  /* push arguments to script */
     status = docall(L, n, LUA_MULTRET);
@@ -609,11 +609,11 @@ static int pushline (lua_State *L, int firstline) {
 static int addreturn (lua_State *L) {
   const char *line = lua_tostring(L, -1);  /* original line */
   const char *retline = lua_pushfstring(L, "return %s;", line);
-  int status = luaL_loadbuffer(L, retline, strlen(retline), "=stdin");
+  int status = luaL_loadbufferx(L, retline, strlen(retline), "=stdin", "t");
   if (status == LUA_OK)
     lua_remove(L, -2);  /* remove modified line */
   else
-    lua_pop(L, 2);  /* pop result from 'luaL_loadbuffer' and modified line */
+    lua_pop(L, 2);  /* pop result from 'luaL_loadbufferx' and modified line */
   return status;
 }
 
@@ -640,7 +640,7 @@ static int multiline (lua_State *L) {
   const char *line = lua_tolstring(L, 1, &len);  /* get first line */
   checklocal(line);
   for (;;) {  /* repeat until gets a complete statement */
-    int status = luaL_loadbuffer(L, line, len, "=stdin");  /* try it */
+    int status = luaL_loadbufferx(L, line, len, "=stdin", "t");  /* try it */
     if (!incomplete(L, status) || !pushline(L, 0))
       return status;  /* should not or cannot try to add continuation line */
     lua_remove(L, -2);  /* remove error message (from incomplete line) */