diff --git a/lapi.c b/lapi.c
index 7bbdf70e..595a4512 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.246 2015/02/11 18:47:22 roberto Exp $
+** $Id: lapi.c,v 2.247 2015/03/06 19:49:50 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -160,7 +160,7 @@ LUA_API const lua_Number *lua_version (lua_State *L) {
 LUA_API int lua_absindex (lua_State *L, int idx) {
   return (idx > 0 || ispseudo(idx))
          ? idx
-         : cast_int(L->top - L->ci->func + idx);
+         : cast_int(L->top - L->ci->func) + idx;
 }
 
 
diff --git a/lbaselib.c b/lbaselib.c
index f3b0a577..40caaa94 100644
--- a/lbaselib.c
+++ b/lbaselib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lbaselib.c,v 1.308 2014/12/08 15:26:55 roberto Exp roberto $
+** $Id: lbaselib.c,v 1.309 2014/12/10 12:26:42 roberto Exp roberto $
 ** Basic library
 ** See Copyright Notice in lua.h
 */
@@ -55,7 +55,7 @@ static const char *b_str2int (const char *s, int base, lua_Integer *pn) {
     return NULL;
   do {
     int digit = (isdigit((unsigned char)*s)) ? *s - '0'
-                   : toupper((unsigned char)*s) - 'A' + 10;
+                   : (toupper((unsigned char)*s) - 'A') + 10;
     if (digit >= base) return NULL;  /* invalid numeral */
     n = n * base + digit;
     s++;
diff --git a/lcode.c b/lcode.c
index eae7e7d7..280d91ea 100644
--- a/lcode.c
+++ b/lcode.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lcode.c,v 2.98 2014/12/19 13:36:32 roberto Exp roberto $
+** $Id: lcode.c,v 2.99 2014/12/29 16:49:25 roberto Exp roberto $
 ** Code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -573,8 +573,8 @@ int luaK_exp2RK (FuncState *fs, expdesc *e) {
     case VKFLT: {
       e->u.info = luaK_numberK(fs, e->u.nval);
       e->k = VK;
-      /* go through */
     }
+    /* FALLTHROUGH */
     case VK: {
      vk:
       if (e->u.info <= MAXINDEXRK)  /* constant fits in 'argC'? */
@@ -793,7 +793,7 @@ static int constfolding (FuncState *fs, int op, expdesc *e1, expdesc *e2) {
 static void codeexpval (FuncState *fs, OpCode op,
                         expdesc *e1, expdesc *e2, int line) {
   lua_assert(op >= OP_ADD);
-  if (op <= OP_BNOT && constfolding(fs, op - OP_ADD + LUA_OPADD, e1, e2))
+  if (op <= OP_BNOT && constfolding(fs, (op - OP_ADD) + LUA_OPADD, e1, e2))
     return;  /* result has been folded */
   else {
     int o1, o2;
@@ -920,11 +920,11 @@ void luaK_posfix (FuncState *fs, BinOpr op,
       break;
     }
     case OPR_EQ: case OPR_LT: case OPR_LE: {
-      codecomp(fs, cast(OpCode, op - OPR_EQ + OP_EQ), 1, e1, e2);
+      codecomp(fs, cast(OpCode, (op - OPR_EQ) + OP_EQ), 1, e1, e2);
       break;
     }
     case OPR_NE: case OPR_GT: case OPR_GE: {
-      codecomp(fs, cast(OpCode, op - OPR_NE + OP_EQ), 0, e1, e2);
+      codecomp(fs, cast(OpCode, (op - OPR_NE) + OP_EQ), 0, e1, e2);
       break;
     }
     default: lua_assert(0);
diff --git a/ldebug.c b/ldebug.c
index 86ee7dae..6e4cdb35 100644
--- a/ldebug.c
+++ b/ldebug.c
@@ -1,5 +1,5 @@
 /*
-** $Id: ldebug.c,v 2.112 2015/03/06 19:49:50 roberto Exp roberto $
+** $Id: ldebug.c,v 2.113 2015/03/11 16:10:41 roberto Exp roberto $
 ** Debug Interface
 ** See Copyright Notice in lua.h
 */
@@ -126,7 +126,7 @@ static const char *upvalname (Proto *p, int uv) {
 
 static const char *findvararg (CallInfo *ci, int n, StkId *pos) {
   int nparams = clLvalue(ci->func)->p->numparams;
-  if (n >= ci->u.l.base - ci->func - nparams)
+  if (n >= cast_int(ci->u.l.base - ci->func) - nparams)
     return NULL;  /* no such vararg */
   else {
     *pos = ci->func + nparams + n;
@@ -172,7 +172,7 @@ LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
       name = luaF_getlocalname(clLvalue(L->top - 1)->p, n, 0);
   }
   else {  /* active function; get information through 'ar' */
-    StkId pos = 0;  /* to avoid warnings */
+    StkId pos = NULL;  /* to avoid warnings */
     name = findlocal(L, ar->i_ci, n, &pos);
     if (name) {
       setobj2s(L, L->top, pos);
@@ -186,7 +186,7 @@ LUA_API const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n) {
 
 
 LUA_API const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n) {
-  StkId pos = 0;  /* to avoid warnings */
+  StkId pos = NULL;  /* to avoid warnings */
   const char *name;
   lua_lock(L);
   swapextra(L);
diff --git a/llex.c b/llex.c
index 8a6ac108..0c3eb4dd 100644
--- a/llex.c
+++ b/llex.c
@@ -1,5 +1,5 @@
 /*
-** $Id: llex.c,v 2.89 2014/11/14 16:06:09 roberto Exp roberto $
+** $Id: llex.c,v 2.90 2015/03/03 18:17:04 roberto Exp roberto $
 ** Lexical Analyzer
 ** See Copyright Notice in lua.h
 */
@@ -283,8 +283,9 @@ static int read_numeral (LexState *ls, SemInfo *seminfo) {
 
 
 /*
-** skip a sequence '[=*[' or ']=*]' and return its number of '='s or
-** -1 if sequence is malformed
+** skip a sequence '[=*[' or ']=*]'; if sequence is wellformed, return
+** its number of '='s; otherwise, return a negative number (-1 iff there
+** are no '='s after initial bracket)
 */
 static int skip_sep (LexState *ls) {
   int count = 0;
@@ -501,8 +502,9 @@ static int llex (LexState *ls, SemInfo *seminfo) {
           read_long_string(ls, seminfo, sep);
           return TK_STRING;
         }
-        else if (sep == -1) return '[';
-        else lexerror(ls, "invalid long string delimiter", TK_STRING);
+        else if (sep != -1)  /* '[=...' missing second bracket */
+          lexerror(ls, "invalid long string delimiter", TK_STRING);
+        return '[';
       }
       case '=': {
         next(ls);
diff --git a/lobject.c b/lobject.c
index 60d1f3d9..3b9bde60 100644
--- a/lobject.c
+++ b/lobject.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lobject.c,v 2.101 2014/12/26 14:43:45 roberto Exp roberto $
+** $Id: lobject.c,v 2.102 2015/02/05 17:15:33 roberto Exp roberto $
 ** Some generic functions over Lua objects
 ** See Copyright Notice in lua.h
 */
@@ -150,13 +150,13 @@ void luaO_arith (lua_State *L, int op, const TValue *p1, const TValue *p2,
   }
   /* could not perform raw operation; try metamethod */
   lua_assert(L != NULL);  /* should not fail when folding (compile time) */
-  luaT_trybinTM(L, p1, p2, res, cast(TMS, op - LUA_OPADD + TM_ADD));
+  luaT_trybinTM(L, p1, p2, res, cast(TMS, (op - LUA_OPADD) + TM_ADD));
 }
 
 
 int luaO_hexavalue (int c) {
   if (lisdigit(c)) return c - '0';
-  else return ltolower(c) - 'a' + 10;
+  else return (ltolower(c) - 'a') + 10;
 }
 
 
@@ -243,7 +243,7 @@ static const char *l_str2d (const char *s, lua_Number *result) {
     *result = lua_strx2number(s, &endptr);
   else
     *result = lua_str2number(s, &endptr);
-  if (endptr == s) return 0;  /* nothing recognized */
+  if (endptr == s) return NULL;  /* nothing recognized */
   while (lisspace(cast_uchar(*endptr))) endptr++;
   return (*endptr == '\0' ? endptr : NULL);  /* OK if no trailing characters */
 }
@@ -289,7 +289,7 @@ size_t luaO_str2num (const char *s, TValue *o) {
   }
   else
     return 0;  /* conversion failed */
-  return (e - s + 1);  /* success; return string size */
+  return (e - s) + 1;  /* success; return string size */
 }
 
 
diff --git a/lstrlib.c b/lstrlib.c
index 28c2bf28..3fc5be98 100644
--- a/lstrlib.c
+++ b/lstrlib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstrlib.c,v 1.225 2015/02/05 17:50:24 roberto Exp roberto $
+** $Id: lstrlib.c,v 1.226 2015/02/09 18:05:46 roberto Exp roberto $
 ** Standard library for string operations and pattern-matching
 ** See Copyright Notice in lua.h
 */
@@ -70,7 +70,7 @@ static int str_sub (lua_State *L) {
   if (start < 1) start = 1;
   if (end > (lua_Integer)l) end = l;
   if (start <= end)
-    lua_pushlstring(L, s + start - 1, (size_t)(end - start + 1));
+    lua_pushlstring(L, s + start - 1, (size_t)(end - start) + 1);
   else lua_pushliteral(L, "");
   return 1;
 }
@@ -149,9 +149,9 @@ static int str_byte (lua_State *L) {
   if (posi < 1) posi = 1;
   if (pose > (lua_Integer)l) pose = l;
   if (posi > pose) return 0;  /* empty interval; return no values */
-  n = (int)(pose -  posi + 1);
-  if (posi + n <= pose)  /* arithmetic overflow? */
+  if (pose - posi >= INT_MAX)  /* arithmetic overflow? */
     return luaL_error(L, "string slice too long");
+  n = (int)(pose -  posi) + 1;
   luaL_checkstack(L, n, "string slice too long");
   for (i=0; i<n; i++)
     lua_pushinteger(L, uchar(s[posi+i-1]));
@@ -499,7 +499,7 @@ static const char *match (MatchState *ms, const char *s, const char *p) {
             }
             case '+':  /* 1 or more repetitions */
               s++;  /* 1 match already done */
-              /* go through */
+              /* FALLTHROUGH */
             case '*':  /* 0 or more repetitions */
               s = max_expand(ms, s, p, ep);
               break;
@@ -554,7 +554,7 @@ static void push_onecapture (MatchState *ms, int i, const char *s,
     ptrdiff_t l = ms->capture[i].len;
     if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");
     if (l == CAP_POSITION)
-      lua_pushinteger(ms->L, ms->capture[i].init - ms->src_init + 1);
+      lua_pushinteger(ms->L, (ms->capture[i].init - ms->src_init) + 1);
     else
       lua_pushlstring(ms->L, ms->capture[i].init, l);
   }
@@ -598,8 +598,8 @@ static int str_find_aux (lua_State *L, int find) {
     /* do a plain search */
     const char *s2 = lmemfind(s + init - 1, ls - (size_t)init + 1, p, lp);
     if (s2) {
-      lua_pushinteger(L, s2 - s + 1);
-      lua_pushinteger(L, s2 - s + lp);
+      lua_pushinteger(L, (s2 - s) + 1);
+      lua_pushinteger(L, (s2 - s) + lp);
       return 2;
     }
   }
@@ -621,7 +621,7 @@ static int str_find_aux (lua_State *L, int find) {
       lua_assert(ms.matchdepth == MAXCCALLS);
       if ((res=match(&ms, s1, p)) != NULL) {
         if (find) {
-          lua_pushinteger(L, s1 - s + 1);  /* start */
+          lua_pushinteger(L, (s1 - s) + 1);  /* start */
           lua_pushinteger(L, res - s);   /* end */
           return push_captures(&ms, NULL, 0) + 2;
         }
@@ -935,8 +935,8 @@ static const char *scanformat (lua_State *L, const char *strfrmt, char *form) {
   if (isdigit(uchar(*p)))
     luaL_error(L, "invalid format (width or precision too long)");
   *(form++) = '%';
-  memcpy(form, strfrmt, (p - strfrmt + 1) * sizeof(char));
-  form += p - strfrmt + 1;
+  memcpy(form, strfrmt, ((p - strfrmt) + 1) * sizeof(char));
+  form += (p - strfrmt) + 1;
   *form = '\0';
   return p;
 }
@@ -1335,7 +1335,7 @@ static int str_pack (lua_State *L) {
         totalsize += len + 1;
         break;
       }
-      case Kpadding: luaL_addchar(&b, LUA_PACKPADBYTE);  /* go through */
+      case Kpadding: luaL_addchar(&b, LUA_PACKPADBYTE);  /* FALLTHROUGH */
       case Kpaddalign: case Knop:
         arg--;  /* undo increment */
         break;