diff --git a/ChangeLog b/ChangeLog
index 312e9e3fd3..6f9f488d4f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon May 23 20:20:12 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* ext/bigdecimal/bigdecimal.c (isfinite): get rid of a warning on
+	  cygwin. [Bug #12417][ruby-core:75691]
+
 Mon May 23 19:41:27 2016  Kazuki Yamaguchi  <k@rhe.jp>
 
 	* ext/openssl/ossl_rand.c (ossl_rand_egd, ossl_rand_egd_bytes):
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 1354242b0b..c9afdf3e04 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -30,7 +30,7 @@
 #include <ieeefp.h>
 #endif
 
-#if !defined(HAVE_ISFINITE) && defined(HAVE_FINITE)
+#if !defined(HAVE_ISFINITE) && defined(HAVE_FINITE) && !defined(isfinite)
 # define isfinite(x) finite(x)
 #endif