diff --git a/roles/ipareplica/library/ipareplica_setup_ca.py b/roles/ipareplica/library/ipareplica_setup_ca.py
index 951bcbe2..01d00a8e 100644
--- a/roles/ipareplica/library/ipareplica_setup_ca.py
+++ b/roles/ipareplica/library/ipareplica_setup_ca.py
@@ -147,7 +147,7 @@ def main():
             _top_dir=dict(required=True),
             _ca_subject=dict(required=True),
             _subject_base=dict(required=True),
-            _random_serial_numbers=dict(required=True),
+            _random_serial_numbers=dict(required=True, type='bool'),
             dirman_password=dict(required=True, no_log=True),
             config_setup_ca=dict(required=True, type='bool'),
             config_master_host_name=dict(required=True),
diff --git a/roles/ipaserver/library/ipaserver_prepare.py b/roles/ipaserver/library/ipaserver_prepare.py
index f7590be8..e75b6858 100644
--- a/roles/ipaserver/library/ipaserver_prepare.py
+++ b/roles/ipaserver/library/ipaserver_prepare.py
@@ -231,7 +231,7 @@ def main():
     # in the _setup_ca module and also some others.
     options._subject_base = None
     options._ca_subject = None
-    options._random_serial_numbers = None
+    options._random_serial_numbers = False
 
     # set values ####################################################
 
diff --git a/roles/ipaserver/library/ipaserver_setup_ca.py b/roles/ipaserver/library/ipaserver_setup_ca.py
index 5863f4bc..0b03f619 100644
--- a/roles/ipaserver/library/ipaserver_setup_ca.py
+++ b/roles/ipaserver/library/ipaserver_setup_ca.py
@@ -207,7 +207,7 @@ def main():
             ca_subject=dict(required=False),
             _ca_subject=dict(required=False),
             ca_signing_algorithm=dict(required=False),
-            _random_serial_numbers=dict(required=True),
+            _random_serial_numbers=dict(required=True, type='bool'),
             # dns
             reverse_zones=dict(required=False, type='list', default=[]),
             no_reverse=dict(required=False, type='bool', default=False),