diff --git a/CHANGES b/CHANGES
index c2fa118cb3..aeadf4df33 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,10 @@
+2463.   [port]          linux: POSIX doesn't include the IPv6 Advanced Socket
+			API and glibc hides parts of the IPv6 Advanced Socket
+			API as a result.  This is stupid as it breaks how the
+			two halves (Basic and Advanced) of the IPv6 Socket API				were designed to be used but we have to live with it.
+			Define _GNU_SOURCE to pull in the IPv6 Advanced Socket
+			API. [RT #18388]
+
 2462.	[doc]		Document -m (enable memory usage debugging)
 			option for dig. [RT #18757]
 
diff --git a/configure.in b/configure.in
index 01b1e0256a..7540bb3ce7 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(1)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl
 
-AC_REVISION($Revision: 1.453 $)
+AC_REVISION($Revision: 1.454 $)
 
 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.59)
@@ -244,6 +244,15 @@ case "$host" in
 		STD_CDEFINES="$STD_CDEFINES -D_XPG4_2 -D__EXTENSIONS__"
 		CPPFLAGS="$CPPFLAGS -D_XPG4_2 -D__EXTENSIONS__"
 		;;
+	# POSIX doesn't include the IPv6 Advanced Socket API and glibc hides
+	# parts of the IPv6 Advanced Socket API as a result.  This is stupid
+	# as it breaks how the two halves (Basic and Advanced) of the IPv6
+	# Socket API were designed to be used but we have to live with it.
+	# Define _GNU_SOURCE to pull in the IPv6 Advanced Socket API.
+	*-linux*)
+		STD_CDEFINES="$STD_CDEFINES -D_GNU_SOURCE"
+		CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"
+		;;
 esac
 
 AC_HEADER_STDC