diff --git a/lib/jekyll/drops/drop.rb b/lib/jekyll/drops/drop.rb
index dfb35d20..6227213e 100644
--- a/lib/jekyll/drops/drop.rb
+++ b/lib/jekyll/drops/drop.rb
@@ -102,8 +102,8 @@ module Jekyll
       #
       # Returns true if the given key is present
       def key?(key)
-        if self.class.mutable && @mutations.key?(key)
-          true
+        if self.class.mutable
+          @mutations.key?(key)
         else
           respond_to?(key) || fallback_data.key?(key)
         end
diff --git a/lib/jekyll/excerpt.rb b/lib/jekyll/excerpt.rb
index 2d53307e..c181cb68 100644
--- a/lib/jekyll/excerpt.rb
+++ b/lib/jekyll/excerpt.rb
@@ -7,7 +7,8 @@ module Jekyll
     attr_writer   :output
 
     def_delegators :@doc, :site, :name, :ext, :relative_path, :extname,
-                          :render_with_liquid?, :collection, :related_posts, :url
+                          :render_with_liquid?, :collection, :related_posts,
+                          :url, :next_doc, :previous_doc
 
     # Initialize this Excerpt instance.
     #