diff --git a/test/lib/aux.sh b/test/lib/aux.sh
index 9420528b1..7587c4beb 100644
--- a/test/lib/aux.sh
+++ b/test/lib/aux.sh
@@ -691,6 +691,7 @@ can_use_16T()
 # i.e.   dm_target_at_least  dm-thin-pool  1 0
 target_at_least()
 {
+	rm -f debug.log
 	case "$1" in
 	  dm-*) modprobe "$1" || true ;;
 	esac