diff --git a/core/string.rbs b/core/string.rbs
index e020147..fadf996 100644
--- a/core/string.rbs
+++ b/core/string.rbs
@@ -42,6 +42,8 @@ class String < Object
          | (Integer nth, Integer len, String val) -> String
   #      | (Range range, String val) -> String
 
+  def b: () -> String
+
   def chomp: () -> String
 
   def chomp!: () -> self?
@@ -83,6 +85,8 @@ class String < Object
 
   # TODO: Symbol
   # def to_sym: () -> Symbol
+  #
+  # alias intern to_sym
 
   def tr: (String pattern, String replace) -> String
 
diff --git a/test/string.rb b/test/string.rb
index 50c81d8..ff41d9d 100644
--- a/test/string.rb
+++ b/test/string.rb
@@ -46,6 +46,8 @@
 'abcdef'[3] = 'D'
 'abcdef'[3, 3] = 'defghi'
 
+'abcdef'.b
+
 "abcdef\n".chomp
 
 "abcdef\n".chomp!