diff --git a/test/Makefile b/test/Makefile
index 228feee7a..e9b9562ac 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -1,6 +1,7 @@
 RM := rm -f --one-file-system
 
 ZDTM_ARGS ?= -C
+export ZDTM_ARGS
 
 .FORCE: