--- ./configure.ac.orig	2013-11-25 20:49:56.000000000 +0100
+++ ./configure.ac	2014-02-20 17:14:50.000000000 +0100
@@ -3,7 +3,7 @@
 AC_SUBST(OPENEXR_VIEWERS_VERSION, 2.1.0)
 AC_CANONICAL_HOST
 AC_CONFIG_SRCDIR(playexr/main.cpp)
-AM_CONFIG_HEADER(config/OpenEXR_ViewersConfig.h)
+AC_CONFIG_HEADERS(config/OpenEXR_ViewersConfig.h)
 AM_INIT_AUTOMAKE(1.6.3)  dnl Require automake 1.6.3 or better
 AM_MAINTAINER_MODE
 
@@ -194,7 +194,10 @@
 dnl
 dnl check for Cg
 dnl
-if test "${have_fltk}" = yes; then
+AC_ARG_ENABLE(cg, AC_HELP_STRING([--enable-cg],
+  [enable nvidia cg support [[default=check]]]), [want_cg="${enableval}"], [want_cg=yes])
+
+if test "${have_fltk}" = yes -a "${want_cg}" != "no"; then
   AM_PATH_CG(have_cg=yes, have_cg=no)
   if test "${have_cg}" = yes; then
     AC_DEFINE(HAVE_FRAGMENT_SHADERS)