--- a/demo/Makefile.am
+++ b/demo/Makefile.am
@@ -17,7 +17,7 @@
     $(NULL)
 c_demo_CFLAGS = $(FT2_CFLAGS) $(GL_CFLAGS)
 c_demo_LDFLAGS = $(FT2_LIBS) $(GLUT_LIBS)
-c_demo_LDADD = ../src/libftgl.la
+c_demo_LDADD = ../src/libftgl.la -lm
 
 FTGLDemo_SOURCES = \
 	FTGLDemo.cpp \