--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@
 AC_INIT(UNAFold, 3.8, markhn@rpi.edu)
 AC_CONFIG_SRCDIR(src/hybrid.c)
 AC_CONFIG_AUX_DIR(config)
-AM_CONFIG_HEADER(config.h:config.in)
+AC_CONFIG_HEADERS(config.h:config.in)
 AM_INIT_AUTOMAKE
 AC_CANONICAL_BUILD
 AC_PROG_CC
@@ -12,7 +12,6 @@
 if test -z "$PERL"; then
    AC_MSG_ERROR(Perl not found)
 fi
-AC_PROG_PERL_VERSION(5.6.1, , AC_MSG_ERROR(Perl 5.6.1 or better is required))
 AC_CHECK_PROG(GNUPLOT, gnuplot, [system('gnuplot', \"\$prefix.gp\") == 0 or die $!;])
 
 AC_MSG_CHECKING(whether compiler needs -mieee)
@@ -28,6 +27,7 @@
 
 
 # Checks for libraries.
+AX_CHECK_GL
 AX_CHECK_GLUT
 AM_CONDITIONAL(GLUT, test -n "$GLUT_LIBS")
 AX_CHECK_GD
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -33,9 +33,9 @@
 endif GLUT
 
 hybrid_plot_ng_SOURCES = hybrid-plot-ng.c getopt.h util.h xmalloc.h
-hybrid_plot_ng_CFLAGS = @GD_CFLAGS@
+hybrid_plot_ng_CFLAGS = @GD_CFLAGS@ $(GL_CFLAGS)
 hybrid_plot_ng_LDFLAGS = @GD_LDFLAGS@
-hybrid_plot_ng_LDADD = getopt.$(OBJEXT) getopt1.$(OBJEXT) xmalloc.$(OBJEXT) @GD_LIBS@ -lm
+hybrid_plot_ng_LDADD = getopt.$(OBJEXT) getopt1.$(OBJEXT) xmalloc.$(OBJEXT) @GD_LIBS@ $(GL_LIBS) -lm
 
 sbs_SOURCES = getopt.c getopt1.c energy.c xmalloc.c sbs.c energy.h getopt.h xmalloc.h
 sbs_LDADD = -lm