diff --git a/src/testdir/Make_all.mak b/src/testdir/Make_all.mak
index f198217..fbdc3c7 100644
--- a/src/testdir/Make_all.mak
+++ b/src/testdir/Make_all.mak
@@ -150,6 +150,7 @@
 	test_fnameescape \
 	test_fnamemodify \
 	test_fold \
+	test_format \
 	test_functions \
 	test_function_lists \
 	test_ga \