Index: xfce4-session-4.8.2/engines/balou/Makefile.am
===================================================================
--- xfce4-session-4.8.2.orig/engines/balou/Makefile.am	2011-09-13 18:17:10.000000000 +0200
+++ xfce4-session-4.8.2/engines/balou/Makefile.am	2011-09-13 23:21:51.910831369 +0200
@@ -29,6 +29,7 @@
 	-module
 
 libbalou_la_LIBADD =							\
+	-lm															\
 	$(top_builddir)/libxfsm/libxfsm-4.6.la				\
 	$(LIBXFCE4UI_LIBS)						\
 	$(XFCONF_LIBS)