diff --git a/ChangeLog b/ChangeLog
index d68d1e27cf..7646df4eb8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri May  1 13:18:01 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* eval_intern.h (_longjmp): never return.  see [ruby-core:23241]
+
 Fri May  1 01:31:19 2009  Tanaka Akira  <akr@fsij.org>
 
 	* ext/extmk.rb: use RbConfig instead of Config.
diff --git a/eval_intern.h b/eval_intern.h
index a9d29ff5fb..03660a6ed9 100644
--- a/eval_intern.h
+++ b/eval_intern.h
@@ -67,7 +67,12 @@ char *strrchr(const char *, const char);
 #define ruby_setjmp(env) RUBY_SETJMP(env)
 #define ruby_longjmp(env,val) RUBY_LONGJMP(env,val)
 #ifdef __CYGWIN__
-int _setjmp(), _longjmp();
+# ifndef _setjmp
+int _setjmp(jmp_buf);
+# endif
+# ifndef _longjmp
+NORETURN(void _longjmp(jmp_buf, int));
+# endif
 #endif
 
 #include <sys/types.h>