diff --git a/ChangeLog b/ChangeLog
index af148668ee..2c182b32f9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Oct 23 15:46:09 2015  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* string.c: Added method signature to include hash. It's inconsistency
+	  with `gsub` method signature.
+	  [ci skip][fix GH-1023] Patch by @danielevans
+
 Fri Oct 23 15:25:51 2015  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* lib/net/imap.rb: remove an empty comment line and -*-.
diff --git a/string.c b/string.c
index af744c7607..eb16998c0a 100644
--- a/string.c
+++ b/string.c
@@ -4628,6 +4628,7 @@ str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 /*
  *  call-seq:
  *     str.gsub!(pattern, replacement)        -> str or nil
+ *     str.gsub!(pattern, hash)               -> str or nil
  *     str.gsub!(pattern) {|match| block }    -> str or nil
  *     str.gsub!(pattern)                     -> an_enumerator
  *