diff --git a/ChangeLog b/ChangeLog
index 9a6cf0053f..bf2184cc81 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul  6 04:05:59 2012  Eric Hodel  <drbrain@segment7.net>
+
+	* ext/zlib/zlib.c (zstream_expand_buffer_without_gvl):  Use
+	  ruby_xrealloc() to avoid crash with CALC_EXACT_MALLOC_SIZE.
+
 Thu Jul  5 17:32:19 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* internal.h: move ThreadShield declarations from intern.h.
diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index 73f3f7c5f0..1b651d1c08 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -679,7 +679,7 @@ zstream_expand_buffer_without_gvl(struct zstream *z)
 
 	len = z->buf_filled + inc;
 
-	new_str = realloc(RSTRING(z->buf)->as.heap.ptr, len + 1);
+	new_str = ruby_xrealloc(RSTRING(z->buf)->as.heap.ptr, len + 1);
 
 	if (!new_str)
 	    return 0;