diff --git a/Makefile.am b/Makefile.am
index aa2168070364e3ba909fb04e5f13bfc6deb10ff5..51e3abf384a69fb7c5ee3e91f2e6580d4329c723 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -88,3 +88,4 @@ code-coverage-clean:
 endif
 
 .PHONY: check-code-coverage code-coverage-initial code-coverage-capture code-coverage-html code-coverage-summary code-coverage-clean singlehtml install-singlehtml
+.NOTPARALLEL: clean