diff --git a/regcomp.c b/regcomp.c
index 3b738b1a67..0ecf162556 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -4213,89 +4213,6 @@ restart:
   return r;
 }
 
-#ifndef USE_SUNDAY_QUICK_SEARCH
-/* set skip map for Boyer-Moore search */
-static int
-set_bm_skip(UChar* s, UChar* end, regex_t* reg,
-            UChar skip[], int** int_skip, int ignore_case)
-{
-  OnigDistance i, len;
-  int clen, flen, n, j, k;
-  UChar *p, buf[ONIGENC_MBC_CASE_FOLD_MAXLEN];
-  OnigCaseFoldCodeItem items[ONIGENC_GET_CASE_FOLD_CODES_MAX_NUM];
-  OnigEncoding enc = reg->enc;
-
-  len = end - s;
-  if (len < ONIG_CHAR_TABLE_SIZE) {
-    for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++) skip[i] = (UChar )len;
-
-    n = 0;
-    for (i = 0; i < len - 1; i += clen) {
-      p = s + i;
-      if (ignore_case)
-        n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
-                                               p, end, items);
-      clen = enclen(enc, p, end);
-      if (p + clen > end)
-        clen = (int )(end - p);
-
-      for (j = 0; j < n; j++) {
-        if ((items[j].code_len != 1) || (items[j].byte_len != clen))
-          return 1;  /* different length isn't supported. */
-        flen = ONIGENC_CODE_TO_MBC(enc, items[j].code[0], buf[j]);
-        if (flen != clen)
-          return 1;  /* different length isn't supported. */
-      }
-      for (j = 0; j < clen; j++) {
-        skip[s[i + j]] = (UChar )(len - 1 - i - j);
-        for (k = 0; k < n; k++) {
-          skip[buf[k][j]] = (UChar )(len - 1 - i - j);
-        }
-      }
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN < ONIG_CHAR_TABLE_SIZE
-    /* This should not happen. */
-    return ONIGERR_TYPE_BUG;
-# else
-    if (IS_NULL(*int_skip)) {
-      *int_skip = (int* )xmalloc(sizeof(int) * ONIG_CHAR_TABLE_SIZE);
-      if (IS_NULL(*int_skip)) return ONIGERR_MEMORY;
-    }
-    for (i = 0; i < ONIG_CHAR_TABLE_SIZE; i++) (*int_skip)[i] = (int )len;
-
-    n = 0;
-    for (i = 0; i < len - 1; i += clen) {
-      p = s + i;
-      if (ignore_case)
-        n = ONIGENC_GET_CASE_FOLD_CODES_BY_STR(enc, reg->case_fold_flag,
-                                               p, end, items);
-      clen = enclen(enc, p, end);
-      if (p + clen > end)
-        clen = (int )(end - p);
-
-      for (j = 0; j < n; j++) {
-        if ((items[j].code_len != 1) || (items[j].byte_len != clen))
-          return 1;  /* different length isn't supported. */
-        flen = ONIGENC_CODE_TO_MBC(enc, items[j].code[0], buf[j]);
-        if (flen != clen)
-          return 1;  /* different length isn't supported. */
-      }
-      for (j = 0; j < clen; j++) {
-        (*int_skip)[s[i + j]] = (int )(len - 1 - i - j);
-        for (k = 0; k < n; k++) {
-          (*int_skip)[buf[k][j]] = (int )(len - 1 - i - j);
-        }
-      }
-    }
-# endif
-  }
-  return 0;
-}
-
-#else /* USE_SUNDAY_QUICK_SEARCH */
-
 /* set skip map for Sunday's quick search */
 static int
 set_bm_skip(UChar* s, UChar* end, regex_t* reg,
@@ -4397,7 +4314,6 @@ endcheck:
   }
   return (int)len;
 }
-#endif /* USE_SUNDAY_QUICK_SEARCH */
 
 typedef struct {
   OnigDistance min;  /* min byte length */
diff --git a/regexec.c b/regexec.c
index e5e5f948a9..eec3e23663 100644
--- a/regexec.c
+++ b/regexec.c
@@ -4377,219 +4377,6 @@ slow_search_backward_ic(OnigEncoding enc, int case_fold_flag,
   return (UChar* )NULL;
 }
 
-#ifndef USE_SUNDAY_QUICK_SEARCH
-/* Boyer-Moore-Horspool search applied to a multibyte string */
-static UChar*
-bm_search_notrev(regex_t* reg, const UChar* target, const UChar* target_end,
-                 const UChar* text, const UChar* text_end,
-                 const UChar* text_range)
-{
-  const UChar *s, *se, *t, *p, *end;
-  const UChar *tail;
-  ptrdiff_t skip, tlen1;
-
-# ifdef ONIG_DEBUG_SEARCH
-  fprintf(stderr, "bm_search_notrev: text: %"PRIuPTR" (%p), text_end: %"PRIuPTR" (%p), text_range: %"PRIuPTR" (%p)\n",
-          (uintptr_t )text, text, (uintptr_t )text_end, text_end, (uintptr_t )text_range, text_range);
-# endif
-
-  tail = target_end - 1;
-  tlen1 = tail - target;
-  end = text_range;
-  if (end + tlen1 > text_end)
-    end = text_end - tlen1;
-
-  s = text;
-
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = se = s + tlen1;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )s;
-        p--; t--;
-      }
-      skip = reg->map[*se];
-      t = s;
-      do {
-        s += enclen(reg->enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = se = s + tlen1;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )s;
-        p--; t--;
-      }
-      skip = reg->int_map[*se];
-      t = s;
-      do {
-        s += enclen(reg->enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-# endif
-  }
-
-  return (UChar* )NULL;
-}
-
-/* Boyer-Moore-Horspool search */
-static UChar*
-bm_search(regex_t* reg, const UChar* target, const UChar* target_end,
-          const UChar* text, const UChar* text_end, const UChar* text_range)
-{
-  const UChar *s, *t, *p, *end;
-  const UChar *tail;
-
-# ifdef ONIG_DEBUG_SEARCH
-  fprintf(stderr, "bm_search: text: %"PRIuPTR" (%p), text_end: %"PRIuPTR" (%p), text_range: %"PRIuPTR" (%p)\n",
-          (uintptr_t )text, text, (uintptr_t )text_end, text_end, (uintptr_t )text_range, text_range);
-# endif
-
-  end = text_range + (target_end - target) - 1;
-  if (end > text_end)
-    end = text_end;
-
-  tail = target_end - 1;
-  s = text + (target_end - target) - 1;
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = s;
-      t = tail;
-# ifdef ONIG_DEBUG_SEARCH
-      fprintf(stderr, "bm_search_loop: pos: %"PRIdPTR" %s\n",
-          (intptr_t )(s - text), s);
-# endif
-      while (*p == *t) {
-        if (t == target) return (UChar* )p;
-        p--; t--;
-      }
-      s += reg->map[*s];
-    }
-  }
-  else { /* see int_map[] */
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = s;
-      t = tail;
-      while (*p == *t) {
-        if (t == target) return (UChar* )p;
-        p--; t--;
-      }
-      s += reg->int_map[*s];
-    }
-# endif
-  }
-  return (UChar* )NULL;
-}
-
-/* Boyer-Moore-Horspool search applied to a multibyte string (ignore case) */
-static UChar*
-bm_search_notrev_ic(regex_t* reg, const UChar* target, const UChar* target_end,
-                    const UChar* text, const UChar* text_end,
-                    const UChar* text_range)
-{
-  const UChar *s, *se, *t, *end;
-  const UChar *tail;
-  ptrdiff_t skip, tlen1;
-  OnigEncoding enc = reg->enc;
-  int case_fold_flag = reg->case_fold_flag;
-
-# ifdef ONIG_DEBUG_SEARCH
-  fprintf(stderr, "bm_search_notrev_ic: text: %d (%p), text_end: %d (%p), text_range: %d (%p)\n",
-          (int )text, text, (int )text_end, text_end, (int )text_range, text_range);
-# endif
-
-  tail = target_end - 1;
-  tlen1 = tail - target;
-  end = text_range;
-  if (end + tlen1 > text_end)
-    end = text_end - tlen1;
-
-  s = text;
-
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      se = s + tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               s, se + 1))
-        return (UChar* )s;
-      skip = reg->map[*se];
-      t = s;
-      do {
-        s += enclen(reg->enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-  }
-  else {
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      se = s + tlen1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               s, se + 1))
-        return (UChar* )s;
-      skip = reg->int_map[*se];
-      t = s;
-      do {
-        s += enclen(reg->enc, s, end);
-      } while ((s - t) < skip && s < end);
-    }
-# endif
-  }
-
-  return (UChar* )NULL;
-}
-
-/* Boyer-Moore-Horspool search (ignore case) */
-static UChar*
-bm_search_ic(regex_t* reg, const UChar* target, const UChar* target_end,
-             const UChar* text, const UChar* text_end, const UChar* text_range)
-{
-  const UChar *s, *p, *end;
-  const UChar *tail;
-  OnigEncoding enc = reg->enc;
-  int case_fold_flag = reg->case_fold_flag;
-
-# ifdef ONIG_DEBUG_SEARCH
-  fprintf(stderr, "bm_search_ic: text: %d (%p), text_end: %d (%p), text_range: %d (%p)\n",
-          (int )text, text, (int )text_end, text_end, (int )text_range, text_range);
-# endif
-
-  end = text_range + (target_end - target) - 1;
-  if (end > text_end)
-    end = text_end;
-
-  tail = target_end - 1;
-  s = text + (target_end - target) - 1;
-  if (IS_NULL(reg->int_map)) {
-    while (s < end) {
-      p = s - (target_end - target) + 1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               p, s + 1))
-        return (UChar* )p;
-      s += reg->map[*s];
-    }
-  }
-  else { /* see int_map[] */
-# if OPT_EXACT_MAXLEN >= ONIG_CHAR_TABLE_SIZE
-    while (s < end) {
-      p = s - (target_end - target) + 1;
-      if (str_lower_case_match(enc, case_fold_flag, target, target_end,
-                               p, s + 1))
-        return (UChar* )p;
-      s += reg->int_map[*s];
-    }
-# endif
-  }
-  return (UChar* )NULL;
-}
-
-#else /* USE_SUNDAY_QUICK_SEARCH */
-
 /* Sunday's quick search applied to a multibyte string */
 static UChar*
 bm_search_notrev(regex_t* reg, const UChar* target, const UChar* target_end,
@@ -4808,7 +4595,6 @@ bm_search_ic(regex_t* reg, const UChar* target, const UChar* target_end,
   }
   return (UChar* )NULL;
 }
-#endif /* USE_SUNDAY_QUICK_SEARCH */
 
 #ifdef USE_INT_MAP_BACKWARD
 static int
diff --git a/regint.h b/regint.h
index 75abfba235..9924e5f62a 100644
--- a/regint.h
+++ b/regint.h
@@ -86,7 +86,6 @@
 /* #define USE_OP_PUSH_OR_JUMP_EXACT */
 #define USE_QTFR_PEEK_NEXT
 #define USE_ST_LIBRARY
-#define USE_SUNDAY_QUICK_SEARCH
 
 #define INIT_MATCH_STACK_SIZE                     160
 #define DEFAULT_MATCH_STACK_LIMIT_SIZE              0 /* unlimited */