diff --git a/regress/Makefile b/regress/Makefile
index deb8ae45..3775a711 100644
--- a/regress/Makefile
+++ b/regress/Makefile
@@ -1,6 +1,7 @@
 TESTS!= echo *.sh
 
 .PHONY: all $(TESTS)
+.NOTPARALLEL: all $(TESTS)
 
 all: $(TESTS)