diff --git a/ChangeLog b/ChangeLog
index e9122c1436..11f6e66ada 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun May  9 08:32:56 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* ext/json/generator/generator.c (fbuffer_inc_capa):
+	  fix tha use of REALLOC_N. [ruby-dev:41227]
+
 Sun May  9 09:15:03 2010  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* test/net/imap/test_imap.rb: use IPv4 for
diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index 12e35d10e1..b25c94f8e9 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -339,7 +339,7 @@ static void fbuffer_inc_capa(FBuffer *fb, unsigned int requested)
     for (required = fb->capa; requested > required - fb->len; required <<= 1);
 
     if (required > fb->capa) {
-        fb->ptr = (char *) REALLOC_N((long*) fb->ptr, char, required);
+        REALLOC_N(fb->ptr, char, required);
         fb->capa = required;
     }
 }