diff -r 55beab95170f src/Makefile
--- a/src/Makefile	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/Makefile	Tue Jul 30 15:34:39 2019 +0300
@@ -7,7 +7,8 @@
 PLAT= none
 
 CC= gcc -std=gnu99
-CFLAGS= -O2 -Wall -Wextra -DLUA_COMPAT_5_3 $(SYSCFLAGS) $(MYCFLAGS)
+#CFLAGS= -O2 -Wall -Wextra -DLUA_COMPAT_5_3 $(SYSCFLAGS) $(MYCFLAGS)
+CFLAGS= -O2 -Wall -Wextra $(SYSCFLAGS) $(MYCFLAGS)
 LDFLAGS= $(SYSLDFLAGS) $(MYLDFLAGS)
 LIBS= -lm $(SYSLIBS) $(MYLIBS)
 
diff -r 55beab95170f src/llex.c
--- a/src/llex.c	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/llex.c	Tue Jul 30 15:34:39 2019 +0300
@@ -41,7 +41,7 @@
     "and", "break", "do", "else", "elseif",
     "end", "false", "for", "function", "goto", "if",
     "in", "local", "nil", "not", "or", "repeat",
-    "return", "then", "true", "until", "while",
+    "return", "then", "true", "until", "noupvalues", "while",
     "//", "..", "...", "==", ">=", "<=", "~=",
     "<<", ">>", "::", "<eof>",
     "<number>", "<integer>", "<name>", "<string>"
diff -r 55beab95170f src/llex.h
--- a/src/llex.h	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/llex.h	Tue Jul 30 15:34:39 2019 +0300
@@ -28,7 +28,7 @@
   TK_AND = FIRST_RESERVED, TK_BREAK,
   TK_DO, TK_ELSE, TK_ELSEIF, TK_END, TK_FALSE, TK_FOR, TK_FUNCTION,
   TK_GOTO, TK_IF, TK_IN, TK_LOCAL, TK_NIL, TK_NOT, TK_OR, TK_REPEAT,
-  TK_RETURN, TK_THEN, TK_TRUE, TK_UNTIL, TK_WHILE,
+  TK_RETURN, TK_THEN, TK_TRUE, TK_UNTIL, TK_NOUPVALUES, TK_WHILE,
   /* other terminal symbols */
   TK_IDIV, TK_CONCAT, TK_DOTS, TK_EQ, TK_GE, TK_LE, TK_NE,
   TK_SHL, TK_SHR,
diff -r 55beab95170f src/lparser.c
--- a/src/lparser.c	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/lparser.c	Tue Jul 30 15:34:39 2019 +0300
@@ -368,6 +368,12 @@
     }
     else {  /* not found as local at current level; try upvalues */
       int idx = searchupvalue(fs, n);  /* try existing upvalues */
+      if (fs->noupvalues) {
+        if (strcmp(getstr(n),LUA_ENV)!=0) {
+          var->k=VVOID;
+          return;
+        }
+      }
       if (idx < 0) {  /* not found? */
         singlevaraux(fs->prev, n, var, 0);  /* try upper levels */
         if (var->k == VVOID)  /* not found? */
@@ -667,6 +673,7 @@
   fs->nlocvars = 0;
   fs->nactvar = 0;
   fs->needclose = 0;
+  fs->noupvalues = 0;
   fs->firstlocal = ls->dyd->actvar.n;
   fs->firstlabel = ls->dyd->label.n;
   fs->bl = NULL;
@@ -924,6 +931,10 @@
   }
   parlist(ls);
   checknext(ls, ')');
+  if (ls->t.token==TK_NOUPVALUES) {
+    luaX_next(ls); /* skip noupvalues */
+    new_fs.noupvalues=1;
+  }
   statlist(ls);
   new_fs.f->lastlinedefined = ls->linenumber;
   check_match(ls, TK_END, TK_FUNCTION, line);
diff -r 55beab95170f src/lparser.h
--- a/src/lparser.h	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/lparser.h	Tue Jul 30 15:34:39 2019 +0300
@@ -141,6 +141,7 @@
   lu_byte freereg;  /* first free register */
   lu_byte iwthabs;  /* instructions issued since last absolute line info */
   lu_byte needclose;  /* function needs to close upvalues when returning */
+  lu_byte noupvalues;
 } FuncState;
 
 
diff -r 55beab95170f src/lua.h
--- a/src/lua.h	Mon Jul 15 19:07:40 2019 +0300
+++ b/src/lua.h	Tue Jul 30 15:34:39 2019 +0300
@@ -18,7 +18,7 @@
 
 #define LUA_VERSION_MAJOR	"5"
 #define LUA_VERSION_MINOR	"4"
-#define LUA_VERSION_RELEASE	"0"
+#define LUA_VERSION_RELEASE	"0+noupvalues"
 
 #define LUA_VERSION_NUM			504
 #define LUA_VERSION_RELEASE_NUM		(LUA_VERSION_NUM * 100 + 0)