diff --git a/src/Makefile b/src/Makefile
index 938425f..ceed541 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -81,33 +81,31 @@ none:
 freebsd:
 	$(MAKE) -C luasocket bsd
 	$(MAKE) -C luasec bsd
-	$(MAKE) all MYCFLAGS="-DLUA_USE_POSIX" MYLIBS="-Wl,-E -lncursesw"
+	$(MAKE) all MYLIBS="-Wl,-E -lncursesw"
 
 linux:
 	$(MAKE) -C lcurses CC="$(CC)" CFLAGS="$(CFLAGS)"
 	$(MAKE) -C luasocket linux
 	$(MAKE) -C luasec linux
-	$(MAKE) all MYCFLAGS="-Wpedantic -DLUA_USE_POSIX" MYLIBS="-Wl,-E -lncursesw"
+	$(MAKE) all MYCFLAGS=-Wpedantic MYLIBS="-Wl,-E -lncursesw"
 
 macosx:
 	$(MAKE) -C lcurses CC="$(CC)" CFLAGS="$(CFLAGS)"
 	$(MAKE) -C luasocket macosx
 	$(MAKE) -C luasec macosx
-	$(MAKE) all MYCFLAGS="-Wpedantic -DLUA_USE_POSIX" MYLIBS="-L/usr/local/opt/openssl@3/lib -lncurses"
-# use this on Mac OS X 10.3-
-#	$(MAKE) all MYCFLAGS=-DLUA_USE_POSIX
+	$(MAKE) all MYCFLAGS=-Wpedantic MYLIBS="-L/usr/local/opt/openssl@3/lib -lncurses"
 
 openbsd:
 	$(MAKE) -C lcurses CC="$(CC)" CFLAGS="$(CFLAGS)"
 	$(MAKE) -C luasocket bsd
 	$(MAKE) -C luasec bsd
-	$(MAKE) all MYCFLAGS="-DLUA_USE_POSIX" MYLIBS="-Wl,-E -lncurses"
+	$(MAKE) all MYLIBS="-Wl,-E -lncurses"
 
 netbsd:
 	$(MAKE) -C lcurses CC="$(CC)" CFLAGS="$(CFLAGS)"
 	$(MAKE) -C luasocket bsd
 	$(MAKE) -C luasec bsd
-	$(MAKE) all MYCFLAGS="-DLUA_USE_POSIX" MYLIBS="-Wl,-E -lcurses"
+	$(MAKE) all MYLIBS="-Wl,-E -lcurses"
 
 # list targets that do not create files (but not all makes understand .PHONY)
 .PHONY: all $(PLATS) default o a clean depend echo none
diff --git a/src/luaconf.h b/src/luaconf.h
index 13d62a4..3c7eff5 100644
--- a/src/luaconf.h
+++ b/src/luaconf.h
@@ -34,17 +34,10 @@
 #endif
 
 
-/*
-@@ LUA_USE_POSIX includes all functionallity listed as X/Open System
-@* Interfaces Extension (XSI).
-** CHANGE it (define it) if your system is XSI compatible.
-*/
-#if defined(LUA_USE_POSIX)
 #define LUA_USE_MKSTEMP
 #define LUA_USE_ISATTY
 #define LUA_USE_POPEN
 #define LUA_USE_ULONGJMP
-#endif
 
 
 /*