diff --git a/src/testdir/Makefile b/src/testdir/Makefile
index f29ec8b..39d8388 100644
--- a/src/testdir/Makefile
+++ b/src/testdir/Makefile
@@ -38,6 +38,7 @@
 		test_autocmd_option.out \
 		test_autoformat_join.out \
 		test_breakindent.out \
+		test_cdo.out \
 		test_changelist.out \
 		test_charsearch.out \
 		test_close_count.out \