diff --git a/lib/prawn/font/ttf.rb b/lib/prawn/font/ttf.rb
index fefef1a3b..08ba62205 100644
--- a/lib/prawn/font/ttf.rb
+++ b/lib/prawn/font/ttf.rb
@@ -25,6 +25,7 @@ def initialize(document, name, options = {})
 
         @ttf = read_ttf_file
         @subsets = TTFunk::SubsetCollection.new(@ttf)
+        @italic_angle = nil
 
         @attributes = {}
         @bounding_boxes = {}