diff --git a/ChangeLog b/ChangeLog
index 29271462d5..2a00110ac6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue May 10 13:07:28 2016  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* configure.in (-fexcess-precision=standard): before r54895 -std=c99
+	  is specified and it implied -fexcess-precision=standard.
+	  Now with -std=gnu99, it should be explicitly specified.
+	  https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
+
 Mon May  9 10:51:59 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* thread.c (rb_thread_atfork_internal): move th to an argument.
diff --git a/configure.in b/configure.in
index 8fb0643312..7a90c18e7b 100644
--- a/configure.in
+++ b/configure.in
@@ -967,7 +967,7 @@ if test "$GCC" = yes; then
     ])
 
     # disable fast-math
-    for oflag in -fno-fast-math -fp-model\ precise; do
+    for oflag in -fno-fast-math -fexcess-precision=standard -fp-model\ precise; do
 	RUBY_TRY_CFLAGS($oflag, [RUBY_APPEND_OPTION(optflags, $oflag)])
     done
 fi