# 
# patch "configure.ac"
#  from [43c8ff541d8d9b3c7a01992b0f3678649dcf001e]
#    to [770dee80aed104ca0636dc6a8d5fbef24f2fdc02]
# 
--- configure.ac
+++ configure.ac
@@ -1,9 +1,14 @@
 AC_INIT(monotone-viz, 0.9)
 
 AC_PROG_OCAML
 AC_PROG_OCAML_TOOLS
 AC_PROG_CAMLP4
+if test -z "$CAMLP4O" ; then
+  AC_MSG_ERROR([
 
+Could not find camlp4o. Camlp4 is required to build monotone-viz.])
+fi
+
 # Check LablGTK
 AC_ARG_WITH([lablgtk-dir], 
 	    AS_HELP_STRING([--with-lablgtk-dir],