--- sbcl-2.6.3/contrib/asdf-module.mk.orig	2026-03-29 18:01:59.000000000 +0200
+++ sbcl-2.6.3/contrib/asdf-module.mk	2026-03-29 21:43:06.195336849 +0200
@@ -12,7 +12,7 @@
 ASD=$(DEST)/$(SYSTEM).asd
 
 ifeq (SunOS,$(UNAME))
-  CFLAGS+=-D_XOPEN_SOURCE=500 -D__EXTENSIONS__
+  CFLAGS+=-D_XOPEN_SOURCE=600 -D__EXTENSIONS__
   PATH:=/usr/xpg4/bin:${PATH}
 endif
 ifeq (CYGWIN,$(findstring CYGWIN,$(UNAME)))