--- testgtk/Makefile.in	2011-08-11 00:54:31.000000000 +0200
+++ testgtk/Makefile.in	2011-08-11 00:54:31.000000000 +0200
@@ -24,7 +24,7 @@
 
 ifeq ($(HAVE_OPENGL),True)
 OPENGL_C_OBJECTS=lw.o
-OPENGL_LIBS= @GL_LIBS@
+OPENGL_LIBS= @GL_LIBS@ -lm
 GTKADA_GL_LIBS=-lgtkada_gl
 else
 OPENGL_C_OBJECTS=