http://bugs.gentoo.org/372229

--- Makefile
+++ Makefile
@@ -28,6 +28,10 @@
 PAMFLAGS += -DHAVE_CONSOLEKIT=1
 endif
 
+ifeq "$(SYSTEMD)" "yes"
+PAMFLAGS += -DHAVE_SYSTEMD=1
+endif
+
 ifeq "$(GNOME_KEYRING)" "yes"
 PAMFLAGS += -DHAVE_GNOME_KEYRING=1
 endif
--- system-login.in
+++ system-login.in
@@ -45,7 +45,10 @@
 #endif
 session		include		system-auth
 #if HAVE_CONSOLEKIT
-session		optional	pam_ck_connector.so nox11
+-session	optional	pam_ck_connector.so nox11
+#endif
+#if HAVE_SYSTEMD
+-session	optional	pam_systemd.so
 #endif
 #if HAVE_GNOME_KEYRING
 session		optional	pam_gnome_keyring.so auto_start