diff --git a/lib/weakref.rb b/lib/weakref.rb
index fbd5d8f..78aad1f 100644
--- a/lib/weakref.rb
+++ b/lib/weakref.rb
@@ -30,9 +30,6 @@ class RefError < StandardError
 
   ##
   # Creates a weak reference to +orig+
-  #
-  # Raises an ArgumentError if the given +orig+ is immutable, such as Symbol,
-  # Integer, or Float.
 
   def initialize(orig)
     case orig