diff --git a/ChangeLog b/ChangeLog
index a5936e2a25..1e8f033de1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri May 21 17:35:15 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (warnflags): add -pedantic if gcc.
+
+	* include/ruby/ruby.h (rb_intern): C90 needs nonempty macro
+	  arguments.
+
 Fri May 21 13:55:46 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (LIBRUBYARG_SHARED): shared library will not be
diff --git a/configure.in b/configure.in
index e3856d6de4..d0ffa7115d 100644
--- a/configure.in
+++ b/configure.in
@@ -386,6 +386,7 @@ if test "$GCC:${warnflags+set}:no" = yes::no; then
     AS_CASE([" $warnflags "],[*" -Wno-missing-field-initializers "*], [wflag=-Wextra],
                              [wflag=-Wall])
     RUBY_TRY_CFLAGS($wflag, [warnflags="$wflag${warnflags+ $warnflags}"])
+    warnflags="-pedantic{warnflags+ $warnflags}"
 fi
 
 test -z "${ac_env_CFLAGS_set}" -a -n "${cflags+set}" && eval CFLAGS="\"$cflags $ARCH_FLAG\""
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index edfa3f41a1..989a2851b0 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1080,7 +1080,7 @@ VALUE rb_id2str(ID);
  * since gcc-2.7.2.3 at least. */
 #define rb_intern(str) \
     (__builtin_constant_p(str) ? \
-        __extension__ (CONST_ID_CACHE(/**/, str)) : \
+        __extension__ (CONST_ID_CACHE((ID), str)) : \
         rb_intern(str))
 #define rb_intern_const(str) \
     (__builtin_constant_p(str) ? \