diff --git a/ChangeLog b/ChangeLog
index 6ad753140f..f18967f739 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Mar 28 21:04:21 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in (ac_cv_func_snprintf, ac_cv_func_vsnprintf):
+	  use own vsnprintf to avoid locale problems and platform
+	  difference.
+
 Sun Mar 28 10:03:51 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/scanf.rb: fix max width modifier for %f.
diff --git a/configure.in b/configure.in
index d195f7521a..5047e9e054 100644
--- a/configure.in
+++ b/configure.in
@@ -888,8 +888,6 @@ main()
 		ac_cv_func_times=yes
 		ac_cv_func_waitpid=yes
 		ac_cv_func_fsync=yes
-		ac_cv_func_snprintf=no
-		ac_cv_func_vsnprintf=no
 		ac_cv_func_seekdir=yes
 		ac_cv_func_telldir=yes
 		ac_cv_func_isinf=yes
@@ -1116,7 +1114,6 @@ main()
 	rb_cv_broken_glibc_ia64_erfc=no)])
 AS_CASE([$rb_cv_broken_glibc_ia64_erfc],[yes],[ac_cv_func_erf=no])
 
-AS_CASE(["$target_os"],[mingw*],[],[AC_REPLACE_FUNCS(vsnprintf)])
 AC_REPLACE_FUNCS(dup2 memmove strerror\
 		 strchr strstr crypt flock\
 		 isnan finite isinf hypot acosh erf tgamma lgamma_r cbrt signbit \
@@ -1128,7 +1125,7 @@ AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall chroot getcwd eacce
 	      setrgid setegid setregid setresgid issetugid pause lchown lchmod\
 	      getpgrp setpgrp getpgid setpgid initgroups getgroups setgroups\
 	      getpriority getrlimit setrlimit sysconf \
-	      dlopen sigprocmask sigaction sigsetjmp _setjmp _longjmp snprintf\
+	      dlopen sigprocmask sigaction sigsetjmp _setjmp _longjmp\
 	      setsid telldir seekdir fchmod cosh sinh tanh log2 round\
 	      setuid setgid daemon select_large_fdset setenv unsetenv\
               mktime timegm gmtime_r clock_gettime gettimeofday\