diff --git a/lib/parser/builders/default.rb b/lib/parser/builders/default.rb
index 26097653e..780be0f91 100644
--- a/lib/parser/builders/default.rb
+++ b/lib/parser/builders/default.rb
@@ -2295,10 +2295,14 @@ def collapse_string_parts?(parts)
           [:str, :dstr].include?(parts.first.type)
     end
 
+    # @param [::Parser::AST::Node] token
+    # @return [String]
     def value(token)
       token[0]
     end
 
+    # @param [::Parser::AST::Node] token
+    # @return [String]
     def string_value(token)
       unless token[0].valid_encoding?
         diagnostic(:error, :invalid_encoding, nil, token[1])