diff --git a/test/Makefile b/test/Makefile
index 4a62d6e1a..8cd48719d 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -14,7 +14,7 @@ all: clean deps $(T) aggregate
 
 clean:
 	@echo "*** $@ ***"
-	-rm -r test-results
+	-rm -rf test-results
 
 $(T):
 	@echo "*** $@ ***"