diff --git a/core/io.rbs b/core/io.rbs
index 69e40b13d..d6abbe911 100644
--- a/core/io.rbs
+++ b/core/io.rbs
@@ -749,7 +749,7 @@ class IO < Object
 
   def self.read: (String name, ?Integer length, ?Integer offset, ?external_encoding: String external_encoding, ?internal_encoding: String internal_encoding, ?encoding: String encoding, ?textmode: untyped textmode, ?binmode: untyped binmode, ?autoclose: untyped autoclose, ?mode: String mode) -> String
 
-  def self.readlines: (String name, ?String sep, ?Integer limit, ?external_encoding: String external_encoding, ?internal_encoding: String internal_encoding, ?encoding: String encoding, ?textmode: untyped textmode, ?binmode: untyped binmode, ?autoclose: untyped autoclose, ?mode: String mode) -> ::Array[String]
+  def self.readlines: (String name, ?String sep, ?Integer limit, ?external_encoding: String external_encoding, ?internal_encoding: String internal_encoding, ?encoding: String encoding, ?textmode: untyped textmode, ?binmode: untyped binmode, ?autoclose: untyped autoclose, ?mode: String mode, ?chomp: boolish) -> ::Array[String]
 
   def self.select: [X, Y, Z] (::Array[X & io]? read_array, ?::Array[Y & io]? write_array, ?::Array[Z & io]? error_array) -> [Array[X], Array[Y], Array[Z]]
                  | [X, Y, Z] (::Array[X & io]? read_array, ?::Array[Y & io]? write_array, ?::Array[Z & io]? error_array, Numeric? timeout) -> [Array[X], Array[Y], Array[Z]]?