diff --git a/app/models/rss_feed.rb b/app/models/rss_feed.rb
index bbbee3c..5b51a3d 100644
--- a/app/models/rss_feed.rb
+++ b/app/models/rss_feed.rb
@@ -8,6 +8,7 @@ class RssFeed < Article
   end
   alias :settings :body
 
+  # The maximum number of articles to be displayed in the RSS feed.
   def limit
     settings[:limit]
   end
@@ -15,19 +16,32 @@ class RssFeed < Article
     settings[:limit] = value
   end
 
+  # FIXME this should be validates_numericality_of, but Rails 1.2.6 does not
+  # support validates_numericality_of with virtual attributes
+  validates_format_of :limit, :with => /^[0-9]+$/, :if => :limit
+
+  # determinates what to include in the feed. Possible values are +:all+
+  # (include everything from the profile) and :parent_and_children (include
+  # only articles that are siblings of the feed).
+  #
+  # The feed itself is never included.
   def include
     settings[:include]
   end
   def include=(value)
     settings[:include] = value
   end
+  validates_inclusion_of :include, :in => [ :all, :parent_and_children ], :if => :include
 
+  # determinates what to include in the feed as items' description. Possible
+  # values are +:body+ (default) and +:abstract+.
   def feed_item_description
     settings[:feed_item_description]
   end
   def feed_item_description=(value)
     settings[:feed_item_description] = value
   end
+  validates_inclusion_of :feed_item_description, :in => [ :body, :abstract ], :if => :feed_item_description
 
   # TODO
   def to_html
diff --git a/test/unit/rss_feed_test.rb b/test/unit/rss_feed_test.rb
index b19d1d9..269bbb7 100644
--- a/test/unit/rss_feed_test.rb
+++ b/test/unit/rss_feed_test.rb
@@ -124,6 +124,46 @@ class RssFeedTest < Test::Unit::TestCase
     feed.data
   end
 
+  should 'limit should only accept integers' do
+    feed = RssFeed.new
+    feed.limit = 'text'
+    feed.valid?
+    assert feed.errors.invalid?(:limit)
+    feed.limit = 10
+    feed.valid?
+    assert !feed.errors.invalid?(:limit)
+  end
+
+  should 'allow only :parent_and_children and :all as include setting' do
+    feed = RssFeed.new
+    feed.include = :something_else
+    feed.valid?
+    assert feed.errors.invalid?(:include)
+
+    feed.include = :parent_and_children
+    feed.valid?
+    assert !feed.errors.invalid?(:include)
+
+    feed.include = :all
+    feed.valid?
+    assert !feed.errors.invalid?(:include)
+  end
+
+  should 'allow only :body and :abstract as feed_item_description' do
+    feed = RssFeed.new
+    feed.feed_item_description = :something_else
+    feed.valid?
+    assert feed.errors.invalid?(:feed_item_description)
+
+    feed.feed_item_description = :body
+    feed.valid?
+    assert !feed.errors.invalid?(:feed_item_description)
+
+    feed.feed_item_description = :abstract
+    feed.valid?
+    assert !feed.errors.invalid?(:feed_item_description)
+  end
+
   should 'provide proper short description' do
     RssFeed.expects(:==).with(Article).returns(true).at_least_once
     assert_not_equal Article.short_description, RssFeed.short_description
--
libgit2 0.21.2