diff --git a/resources/preference.rb b/resources/preference.rb
index ef771a1f..7f734971 100644
--- a/resources/preference.rb
+++ b/resources/preference.rb
@@ -31,7 +31,7 @@ def initialize(*args)
             :pin,
             :pin_priority
 
-attribute :package_name, :kind_of => String, :name_attribute => true
+attribute :package_name, :kind_of => String, :name_attribute => true, :regex => [ /^([a-z]|[A-Z]|[0-9]|_|-|\.)+$/ ]
 attribute :glob, :kind_of => String
 attribute :pin, :kind_of => String
 attribute :pin_priority, :kind_of => String
diff --git a/resources/repository.rb b/resources/repository.rb
index 71a40aa6..1a67e512 100644
--- a/resources/repository.rb
+++ b/resources/repository.rb
@@ -39,7 +39,7 @@ def initialize(*args)
             :uri
 
 # name of the repo, used for source.list filename
-attribute :repo_name, :kind_of => String, :name_attribute => true
+attribute :repo_name, :kind_of => String, :name_attribute => true, :regex => [ /^([a-z]|[A-Z]|[0-9]|_|-|\.)+$/ ]
 attribute :uri, :kind_of => String
 attribute :distribution, :kind_of => String
 attribute :components, :kind_of => Array, :default => []