1 files changed, 1 insertions, 1 deletions
diff --git a/include/ruby/oniguruma.h b/include/ruby/oniguruma.h
index 2530f61427..519c0ac336 100644
--- a/include/ruby/oniguruma.h
+++ b/include/ruby/oniguruma.h
@@ -167,7 +167,7 @@ typedef struct OnigEncodingTypeST {
   int    (*mbc_case_fold)(OnigCaseFoldType flag, const OnigUChar** pp, const OnigUChar* end, OnigUChar* to, const struct OnigEncodingTypeST* enc);
   int    (*apply_all_case_fold)(OnigCaseFoldType flag, OnigApplyAllCaseFoldFunc f, void* arg, const struct OnigEncodingTypeST* enc);
   int    (*get_case_fold_codes_by_str)(OnigCaseFoldType flag, const OnigUChar* p, const OnigUChar* end, OnigCaseFoldCodeItem acs[], const struct OnigEncodingTypeST* enc);
-  int    (*property_name_to_ctype)(const struct OnigEncodingTypeST* enc, OnigUChar* p, OnigUChar* end);
+  int    (*property_name_to_ctype)(const struct OnigEncodingTypeST* enc, const OnigUChar* p, const OnigUChar* end);
   int    (*is_code_ctype)(OnigCodePoint code, OnigCtype ctype, const struct OnigEncodingTypeST* enc);
   int    (*get_ctype_code_range)(OnigCtype ctype, OnigCodePoint* sb_out, const OnigCodePoint* ranges[], const struct OnigEncodingTypeST* enc);
   OnigUChar* (*left_adjust_char_head)(const OnigUChar* start, const OnigUChar* p, const OnigUChar* end, const struct OnigEncodingTypeST* enc);