diff --git a/tests/Makefile.am b/tests/Makefile.am
index 1d95b30c..aa43668d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -15,6 +15,7 @@ dist_noinst_SCRIPTS = common.sh \
                       test-pkcs11-tool-sign-verify.sh \
                       test-pkcs11-tool-allowed-mechanisms.sh
 
+.NOTPARALLEL:
 TESTS = \
         test-manpage.sh \
         test-duplicate-symbols.sh \