diff --git a/ChangeLog b/ChangeLog
index 63284a9a27..47bf30200a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Jan 28 15:24:11 2009  TAKANO Mitsuhiro (takano32)  <tak@no32.tk>
+
+	* math.c: SEGV is caused by implicit rb_to_float declaration
+	  test_complexrational.rb: [BUG] in IA-64 architecture
+
 Tue Jan 27 20:02:07 2009  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/init.c (socks_connect_blocking): moved from
diff --git a/math.c b/math.c
index 63a386360a..c7e79c1a80 100644
--- a/math.c
+++ b/math.c
@@ -15,6 +15,7 @@
 
 VALUE rb_mMath;
 
+extern VALUE rb_to_float(VALUE val);
 #define Need_Float(x) (x) = rb_to_float(x)
 #define Need_Float2(x,y) do {\
     Need_Float(x);\