diff --git a/ChangeLog b/ChangeLog
index 126cac520a..c12c0575c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Sep 22 04:56:18 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/bigdecimal/lib/bigdecimal/*.rb: made module functions.
+
 Tue Sep 22 04:47:37 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/bigdecimal/bigdecimal.c (GetVpValue): support conversion from
diff --git a/ext/bigdecimal/lib/bigdecimal/jacobian.rb b/ext/bigdecimal/lib/bigdecimal/jacobian.rb
index 8d8d583bcf..e4420df158 100644
--- a/ext/bigdecimal/lib/bigdecimal/jacobian.rb
+++ b/ext/bigdecimal/lib/bigdecimal/jacobian.rb
@@ -21,6 +21,8 @@
 # fx is f.values(x).
 #
 module Jacobian
+  module_function
+
   #--
   def isEqual(a,b,zero=0.0,e=1.0e-8)
     aa = a.abs
diff --git a/ext/bigdecimal/lib/bigdecimal/ludcmp.rb b/ext/bigdecimal/lib/bigdecimal/ludcmp.rb
index e18446d55b..9b2c3d2330 100644
--- a/ext/bigdecimal/lib/bigdecimal/ludcmp.rb
+++ b/ext/bigdecimal/lib/bigdecimal/ludcmp.rb
@@ -2,6 +2,8 @@
 # Solves a*x = b for x, using LU decomposition.
 #
 module LUSolve
+  module_function
+
   # Performs LU decomposition of the n by n matrix a.
   def ludecomp(a,n,zero=0,one=1)
     prec = BigDecimal.limit(nil)
diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb
index 635992ef14..191884eb12 100644
--- a/ext/bigdecimal/lib/bigdecimal/math.rb
+++ b/ext/bigdecimal/lib/bigdecimal/math.rb
@@ -29,6 +29,7 @@
 #   puts sin(a,100) # -> 0.10000000000000000000......E1
 #
 module BigMath
+  module_function
 
   # Computes the square root of x to the specified number of digits of
   # precision.
diff --git a/ext/bigdecimal/lib/bigdecimal/newton.rb b/ext/bigdecimal/lib/bigdecimal/newton.rb
index d78c3d7647..cab2fcddff 100644
--- a/ext/bigdecimal/lib/bigdecimal/newton.rb
+++ b/ext/bigdecimal/lib/bigdecimal/newton.rb
@@ -28,6 +28,7 @@ require "bigdecimal/jacobian"
 module Newton
   include LUSolve
   include Jacobian
+  module_function
 
   def norm(fv,zero=0.0)
     s = zero