diff --git a/ChangeLog b/ChangeLog
index fbb6ee172f..6736e1d57d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Jan 17 19:24:25 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* math.c (domain_check): check errno first.
+
 Sat Jan 16 07:17:15 2010  NAKAMURA, Hiroshi  <nahi@ruby-lang.org>
 
 	* ext/zlib/zlib.c: backport r18029 and r21861 from trunk.
diff --git a/math.c b/math.c
index abe5f6c164..93de8b3abe 100644
--- a/math.c
+++ b/math.c
@@ -29,9 +29,9 @@ domain_check(x, msg)
     double x;
     const char *msg;
 {
-    if (!isnan(x)) return;
-    else {
-	if (!errno) {
+    if (!errno) {
+	if (!isnan(x)) return;
+	else {
 #if defined(EDOM)
 	    errno = EDOM;
 #else
diff --git a/version.h b/version.h
index 2c504e73fa..5724992b91 100644
--- a/version.h
+++ b/version.h
@@ -1,7 +1,7 @@
 #define RUBY_VERSION "1.8.8"
-#define RUBY_RELEASE_DATE "2010-01-16"
+#define RUBY_RELEASE_DATE "2010-01-17"
 #define RUBY_VERSION_CODE 188
-#define RUBY_RELEASE_CODE 20100116
+#define RUBY_RELEASE_CODE 20100117
 #define RUBY_PATCHLEVEL -1
 
 #define RUBY_VERSION_MAJOR 1
@@ -9,7 +9,7 @@
 #define RUBY_VERSION_TEENY 8
 #define RUBY_RELEASE_YEAR 2010
 #define RUBY_RELEASE_MONTH 1
-#define RUBY_RELEASE_DAY 16
+#define RUBY_RELEASE_DAY 17
 
 #ifdef RUBY_EXTERN
 RUBY_EXTERN const char ruby_version[];