diff --git a/enc/unicode.c b/enc/unicode.c
index cbfc6cdf58..1c4428a3be 100644
--- a/enc/unicode.c
+++ b/enc/unicode.c
@@ -682,7 +682,7 @@ onigenc_unicode_case_map(OnigCaseFoldType* flagP,
     *pp += codepoint_length;
 
     if (code <= 'z') { /* ASCII comes first */
-      if (code >= 'a' && code <= 'z') {
+      if (code >= 'a' /*&& code <= 'z'*/) {
 	if (flags & ONIGENC_CASE_UPCASE) {
 	  MODIFIED;
 	  if (flags & ONIGENC_CASE_FOLD_TURKISH_AZERI && code == 'i')
diff --git a/regcomp.c b/regcomp.c
index 22dbe5f9d5..664806f085 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -2803,14 +2803,11 @@ get_head_value_node(Node* node, int exact, regex_t* reg)
   case NT_STR:
     {
       StrNode* sn = NSTR(node);
-
       if (sn->end <= sn->s)
         break;
 
-      if (exact != 0 &&
-          !NSTRING_IS_RAW(node) && IS_IGNORECASE(reg->options)) {
-      }
-      else {
+      if (exact == 0 ||
+          NSTRING_IS_RAW(node) || !IS_IGNORECASE(reg->options)) {
         n = node;
       }
     }
@@ -5078,7 +5075,7 @@ optimize_node_left(Node* node, NodeOptInfo* opt, OptEnv* env)
 
         if (NSTRING_IS_DONT_GET_OPT_INFO(node)) {
           int n = onigenc_strlen(env->enc, sn->s, sn->end);
-          max = ONIGENC_MBC_MAXLEN_DIST(env->enc) * (OnigDistance)n;
+          max = (OnigDistance )ONIGENC_MBC_MAXLEN_DIST(env->enc) * (OnigDistance)n;
         }
         else {
           concat_opt_exact_info_str(&opt->exb, sn->s, sn->end,
diff --git a/regexec.c b/regexec.c
index b8d174ec8e..e5e5f948a9 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2742,7 +2742,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
       /* default behavior: return first-matching result. */
       goto finish;
-      NEXT;
 
     CASE(OP_EXACT1)  MOP_IN(OP_EXACT1);
       DATA_ENSURE(1);
@@ -3316,40 +3315,36 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
         if (ON_STR_BEGIN(s) || !ONIGENC_IS_MBC_WORD(encode, sprev, end)) {
           MOP_OUT;
           JUMP;
-        }
+	}
       }
       goto fail;
-      NEXT;
 
     CASE(OP_ASCII_WORD_BEGIN)  MOP_IN(OP_ASCII_WORD_BEGIN);
       if (DATA_ENSURE_CHECK1 && ONIGENC_IS_MBC_ASCII_WORD(encode, s, end)) {
         if (ON_STR_BEGIN(s) || !ONIGENC_IS_MBC_ASCII_WORD(encode, sprev, end)) {
           MOP_OUT;
           JUMP;
-        }
+	}
       }
       goto fail;
-      NEXT;
 
     CASE(OP_WORD_END)  MOP_IN(OP_WORD_END);
       if (!ON_STR_BEGIN(s) && ONIGENC_IS_MBC_WORD(encode, sprev, end)) {
         if (ON_STR_END(s) || !ONIGENC_IS_MBC_WORD(encode, s, end)) {
           MOP_OUT;
           JUMP;
-        }
+	}
       }
       goto fail;
-      NEXT;
 
     CASE(OP_ASCII_WORD_END)  MOP_IN(OP_ASCII_WORD_END);
       if (!ON_STR_BEGIN(s) && ONIGENC_IS_MBC_ASCII_WORD(encode, sprev, end)) {
         if (ON_STR_END(s) || !ONIGENC_IS_MBC_ASCII_WORD(encode, s, end)) {
           MOP_OUT;
           JUMP;
-        }
+	}
       }
       goto fail;
-      NEXT;
 #endif
 
     CASE(OP_BEGIN_BUF)  MOP_IN(OP_BEGIN_BUF);
@@ -3379,10 +3374,9 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 #endif
                 && !ON_STR_END(s)) {
         MOP_OUT;
-        JUMP;
+	JUMP;
       }
       goto fail;
-      NEXT;
 
     CASE(OP_END_LINE)  MOP_IN(OP_END_LINE);
       if (ON_STR_END(s)) {
@@ -3398,10 +3392,9 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       }
       else if (ONIGENC_IS_MBC_NEWLINE_EX(encode, s, str, end, option, 1)) {
         MOP_OUT;
-        JUMP;
+	JUMP;
       }
       goto fail;
-      NEXT;
 
     CASE(OP_SEMI_END_BUF)  MOP_IN(OP_SEMI_END_BUF);
       if (ON_STR_END(s)) {
@@ -3433,7 +3426,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 #endif
       }
       goto fail;
-      NEXT;
 
     CASE(OP_BEGIN_POSITION)  MOP_IN(OP_BEGIN_POSITION);
       if (s != msa->gpos)
@@ -3499,12 +3491,10 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE(OP_BACKREF1)  MOP_IN(OP_BACKREF1);
       mem = 1;
       goto backref;
-      NEXT;
 
     CASE(OP_BACKREF2)  MOP_IN(OP_BACKREF2);
       mem = 2;
       goto backref;
-      NEXT;
 
     CASE(OP_BACKREFN)  MOP_IN(OP_BACKREFN);
       GET_MEMNUM_INC(mem, p);
@@ -3934,7 +3924,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       STACK_GET_REPEAT(mem, stkp);
       si = GET_STACK_INDEX(stkp);
       goto repeat_inc;
-      NEXT;
 
     CASE(OP_REPEAT_INC_NG)  MOP_IN(OP_REPEAT_INC_NG);
       GET_MEMNUM_INC(mem, p); /* mem: OP_REPEAT ID */
@@ -3970,7 +3959,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       STACK_GET_REPEAT(mem, stkp);
       si = GET_STACK_INDEX(stkp);
       goto repeat_inc_ng;
-      NEXT;
 
     CASE(OP_PUSH_POS)  MOP_IN(OP_PUSH_POS);
       STACK_PUSH_POS(s, sprev, pkeep);
@@ -3995,7 +3983,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE(OP_FAIL_POS)  MOP_IN(OP_FAIL_POS);
       STACK_POP_TIL_POS_NOT;
       goto fail;
-      NEXT;
 
     CASE(OP_PUSH_STOP_BT)  MOP_IN(OP_PUSH_STOP_BT);
       STACK_PUSH_STOP_BT;
@@ -4036,7 +4023,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
     CASE(OP_FAIL_LOOK_BEHIND_NOT)  MOP_IN(OP_FAIL_LOOK_BEHIND_NOT);
       STACK_POP_TIL_LOOK_BEHIND_NOT;
       goto fail;
-      NEXT;
 
     CASE(OP_PUSH_ABSENT_POS)  MOP_IN(OP_PUSH_ABSENT_POS);
       /* Save the absent-start-pos and the original end-pos. */
@@ -4098,7 +4084,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 #endif
       STACK_POP_TIL_ABSENT;
       goto fail;
-      NEXT;
 
 #ifdef USE_SUBEXP_CALL
     CASE(OP_CALL)  MOP_IN(OP_CALL);
@@ -4128,7 +4113,6 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
 
     CASE(OP_FINISH)
       goto finish;
-      NEXT;
 
     CASE(OP_FAIL)
       if (0) {