diff --git a/lib/protocol/http/reference.rb b/lib/protocol/http/reference.rb
index d4bec66..dacb608 100644
--- a/lib/protocol/http/reference.rb
+++ b/lib/protocol/http/reference.rb
@@ -75,7 +75,7 @@ def <=> other
 			
 			# Type-cast a reference.
 			#
-			# @parameter reference [Reference, String] The reference to type-cast.
+			# @parameter reference [Reference | String] The reference to type-cast.
 			# @returns [Reference] The type-casted reference.
 			def self.[] reference
 				if reference.is_a? self