diff --git a/ChangeLog b/ChangeLog
index 0bb692be56..e9563ddb0d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Apr  6 01:22:55 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* math.c (ruby_lgamma_r): mswin's lgamma_r also seems to be wrong.
+	  cf. [Bug #12249]
+
 Wed Apr  6 00:53:31 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* math.c (ruby_lgamma_r): fix lgamma(-0.0) on mingw and OSX.
diff --git a/math.c b/math.c
index 9e97f3a2d2..23c6210373 100644
--- a/math.c
+++ b/math.c
@@ -750,7 +750,7 @@ ruby_tgamma(const double d)
 #define tgamma(d) ruby_tgamma(d)
 #endif
 
-#if defined __MINGW32__ || defined __APPLE__
+#if defined _WIN32 || defined __APPLE__
 static inline double
 ruby_lgamma_r(const double d, int *sign)
 {