Index: libcfa/configure
===================================================================
--- libcfa/configure	(revision 2b3d6ffbb6d7766453ab806a83d1e85a3993c145)
+++ libcfa/configure	(revision 6ebc13f8db653fa16139c298e7dd18067bafaaff)
@@ -2970,4 +2970,7 @@
 		CONFIG_CFAFLAGS="-nodebug"
 		CONFIG_BUILDLIB="no"
+	;;
+	*)
+	as_fn_error $? "'Invalid value $CONFIGURATION for \$CONFIGURATION'" "$LINENO" 5
 	;;
 esac