diff -auNr BibTool/AutoConf/makefile.in BibTool-new/AutoConf/makefile.in
--- BibTool/AutoConf/makefile.in	2020-04-13 22:32:40.000000000 +0800
+++ BibTool-new/AutoConf/makefile.in	2024-01-29 18:09:47.041145779 +0800
@@ -234,9 +234,9 @@
 REGEX_DIR  = regex-0.12
 # 
 
-REGEX_DEF  = -DREGEX -I$(REGEX_DIR) -I..
+REGEX_DEF  = -DREGEX
 
-REGEX      = regex$(OBJ)
+REGEX      =
 
 # -------------------------------------------------------
 #  Kpathsea Library support.
@@ -500,8 +500,8 @@
 # __________________________________________________________________
 #  Targets from the GNU Regular Expression Library.
 
-regex$(OBJ): $(REGEX_DIR)$(DIR_SEP)regex.c $(MAKEFILE)
-	$(CC) $(C_FLAGS) -I$(REGEX_DIR) -I.. $(NON_ANSI_DEFS) $(REGEX_DIR)$(DIR_SEP)regex.c $(DONT_LINK) -o $@
+# regex$(OBJ): $(REGEX_DIR)$(DIR_SEP)regex.c $(MAKEFILE)
+# 	$(CC) $(C_FLAGS) -I$(REGEX_DIR) -I.. $(NON_ANSI_DEFS) $(REGEX_DIR)$(DIR_SEP)regex.c $(DONT_LINK) -o $@
 
 
 bibtcl:
@@ -535,7 +535,7 @@
 	(cd test; $(MAKE))
 
 libbibtool.a: $(OLIBFILES)
-	$(AR) $@ $(OLIBFILES) regex.o
+	$(AR) $@ $(OLIBFILES)
 	$(RANLIB) $@
 
 depend:
diff -auNr BibTool/rewrite.c BibTool-new/rewrite.c
--- BibTool/rewrite.c	2020-04-13 22:31:54.000000000 +0800
+++ BibTool-new/rewrite.c	2024-01-29 18:10:26.031482831 +0800
@@ -37,7 +37,8 @@
 #include <bibtool/symbols.h>
 
 #ifdef REGEX
 #include <bibtool/regex.h>
+#define  __USE_GNU
 #endif
 
  typedef struct rULE