--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -4,7 +4,7 @@
 	-DTOMOEGTKDATADIR=\""$(datadir)"/$(PACKAGE)\"
 
 INCLUDES = $(GTK2_CFLAGS) $(TOMOE_CFLAGS) $(GUCHARMAP_CFLAGS)
-LIBS     = $(GTK2_LIBS)   $(TOMOE_LIBS)   $(GUCHARMAP_LIBS)
+LIBS     = $(GTK2_LIBS)   $(TOMOE_LIBS)   $(GUCHARMAP_LIBS)   -lm
 
 lib_LTLIBRARIES = libtomoe-gtk.la
 libtomoe_gtk_la_SOURCES =						\