--- configure.ac.orig	2010-07-03 19:43:46.000000000 +0200
+++ configure.ac	2010-07-03 19:45:59.000000000 +0200
@@ -58,14 +58,25 @@
 AC_SUBST(GNOME_KEYRING_CFLAGS)
 AC_SUBST(GNOME_KEYRING_LIBS)
 
-AC_PATH_PROG(MDASSEMBLER, mdassembler, no)
-AC_PATH_PROG(MONODOCER, monodocer, no)
-if test "x$MONODOCER" = "xno" -o "x$MDASSEMBLER" = "xno"; then
-  enable_monodoc=no
-  doc_sources_dir=
-else
-  enable_monodoc=yes
-  doc_sources_dir="`pkg-config --variable=sourcesdir monodoc`"
+AC_ARG_ENABLE(monodoc, 
+	[AC_HELP_STRING([--enable-monodoc],[install monodoc documents default: yes])],
+	[ENABLE_MONODOC="$enableval"])
+	
+if test "x$ENABLE_MONODOC" != "xno" ; then
+	AC_PATH_PROG(MDASSEMBLER, mdassembler, no)
+	AC_PATH_PROG(MONODOCER, monodocer, no)
+
+	if test "x$MONODOCER" = "xno" -o "x$MDASSEMBLER" = "xno"; then
+		if test "x$ENABLE_MONODOC" = "xyes" ; then
+			AC_MSG_ERROR([monodoc can't be installed even though it was explicitly enabled. mdassembler or monodocer not found.])
+		else
+			enable_monodoc=no
+			doc_sources_dir=
+		fi
+	else
+		enable_monodoc=yes
+		doc_sources_dir="`pkg-config --variable=sourcesdir monodoc`"
+	fi
 fi
 
 AM_CONDITIONAL(ENABLE_MONODOC, test "x$enable_monodoc" = "xyes")