diff --git a/lib/html/pipeline/@mention_filter.rb b/lib/html/pipeline/@mention_filter.rb
index 683f513f..7b754a88 100644
--- a/lib/html/pipeline/@mention_filter.rb
+++ b/lib/html/pipeline/@mention_filter.rb
@@ -62,7 +62,7 @@ def self.mentioned_logins_in(text)
       def call
         result[:mentioned_usernames] ||= []
 
-        doc.search('text()').each do |node|
+        search_text_nodes(doc).each do |node|
           content = node.to_html
           next if !content.include?('@')
           next if has_ancestor?(node, IGNORE_PARENTS)
@@ -118,4 +118,4 @@ def link_to_mentioned_user(login)
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/html/pipeline/emoji_filter.rb b/lib/html/pipeline/emoji_filter.rb
index 4fc551d5..712c4fec 100644
--- a/lib/html/pipeline/emoji_filter.rb
+++ b/lib/html/pipeline/emoji_filter.rb
@@ -15,7 +15,7 @@ class Pipeline
     #   :asset_path (optional) - url path to link to emoji sprite. :file_name can be used as a placeholder for the sprite file name. If no asset_path is set "emoji/:file_name" is used.
     class EmojiFilter < Filter
       def call
-        doc.search('text()').each do |node|
+        search_text_nodes(doc).each do |node|
           content = node.to_html
           next if !content.include?(':')
           next if has_ancestor?(node, %w(pre code))
diff --git a/lib/html/pipeline/filter.rb b/lib/html/pipeline/filter.rb
index 0fe5a831..5467bc06 100644
--- a/lib/html/pipeline/filter.rb
+++ b/lib/html/pipeline/filter.rb
@@ -59,6 +59,13 @@ def doc
         @doc ||= parse_html(html)
       end
 
+      # Searches a Nokogiri::HTML::DocumentFragment for text nodes. If no elements
+      # are found, a second search without root tags is invoked.
+      def search_text_nodes(doc)
+        nodes = doc.xpath('.//text()')
+        nodes.empty? ? doc.xpath('text()') : nodes
+      end
+
       # The String representation of the document. If a DocumentFragment was
       # provided to the Filter, it is serialized into a String when this method is
       # called.
diff --git a/test/html/pipeline/emoji_filter_test.rb b/test/html/pipeline/emoji_filter_test.rb
index e46ac32b..298775ed 100644
--- a/test/html/pipeline/emoji_filter_test.rb
+++ b/test/html/pipeline/emoji_filter_test.rb
@@ -8,6 +8,12 @@ def test_emojify
     doc = filter.call
     assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
   end
+
+  def test_emojify_on_string
+    filter = EmojiFilter.new(":shipit:", {:asset_root => 'https://foo.com'})
+    doc = filter.call
+    assert_match "https://foo.com/emoji/shipit.png", doc.search('img').attr('src').value
+  end
   
   def test_uri_encoding
     filter = EmojiFilter.new("<p>:+1:</p>", {:asset_root => 'https://foo.com'})