diff --git a/Gemfile b/Gemfile
index 2905b9e3f11..7b88dc6a7bd 100644
--- a/Gemfile
+++ b/Gemfile
@@ -46,7 +46,7 @@ gem "manageiq-messaging",                              :require => false, :git =
 gem "manageiq-network_discovery",     "~>0.1.2",       :require => false
 gem "memoist",                        "~>0.15.0",      :require => false
 gem "mime-types",                     "~>2.6.1",       :path => "mime-types-redirector"
-gem "more_core_extensions",           "~>3.3"
+gem "more_core_extensions",           "~>3.5"
 gem "nakayoshi_fork",                 "~>0.0.3"  # provides a more CoW friendly fork (GC a few times before fork)
 gem "net-ldap",                       "~>0.14.0",      :require => false
 gem "net-ping",                       "~>1.7.4",       :require => false
diff --git a/app/models/ext_management_system.rb b/app/models/ext_management_system.rb
index e9b01b6e8c0..2bf22ab2aed 100644
--- a/app/models/ext_management_system.rb
+++ b/app/models/ext_management_system.rb
@@ -76,7 +76,7 @@ def self.supported_types_and_descriptions_hash
 
   validates :name,     :presence => true, :uniqueness => {:scope => [:tenant_id]}
   validates :hostname, :presence => true, :if => :hostname_required?
-  validate :hostname_uniqueness_valid?, :if => :hostname_required?
+  validate :hostname_uniqueness_valid?, :hostname_format_valid?, :if => :hostname_required?
 
   scope :with_eligible_manager_types, ->(eligible_types) { where(:type => eligible_types) }
 
@@ -92,6 +92,11 @@ def hostname_uniqueness_valid?
     errors.add(:hostname, N_("has to be unique per provider type")) if existing_hostnames.include?(hostname.downcase)
   end
 
+  def hostname_format_valid?
+    return if hostname.ipaddress? || hostname.hostname?
+    errors.add(:hostname, _("format is invalid."))
+  end
+
   include NewWithTypeStiMixin
   include UuidMixin
   include EmsRefresh::Manager