diff --git a/tests/db/Makefile.am b/tests/db/Makefile.am
index 9597a0b44..d1cf761bc 100644
--- a/tests/db/Makefile.am
+++ b/tests/db/Makefile.am
@@ -2,6 +2,8 @@
 
 include $(top_srcdir)/Makefile.am.common
 
+.NOTPARALLEL:
+
 noinst_DATA = krb5.conf krb5.conf-sqlite krb5.conf-db3 krb5.conf-db1 krb5.conf-lmdb
 
 noinst_SCRIPTS = have-db
diff --git a/tests/gss/Makefile.am b/tests/gss/Makefile.am
index 2de36bfe2..b9c5ddd60 100644
--- a/tests/gss/Makefile.am
+++ b/tests/gss/Makefile.am
@@ -2,6 +2,8 @@
 
 include $(top_srcdir)/Makefile.am.common
 
+.NOTPARALLEL:
+
 noinst_DATA = krb5.conf new_clients_k5.conf mech
 
 SCRIPT_TESTS = check-basic check-gss check-gssmask check-context check-spnego check-ntlm check-negoex
diff --git a/tests/kdc/Makefile.am b/tests/kdc/Makefile.am
index 09f695348..b74c011ba 100644
--- a/tests/kdc/Makefile.am
+++ b/tests/kdc/Makefile.am
@@ -1,5 +1,7 @@
 include $(top_srcdir)/Makefile.am.common
 
+.NOTPARALLEL:
+
 noinst_DATA = \
 	an2ln-db.txt \
 	kdc-tester4.json \