diff --git a/ChangeLog b/ChangeLog
index 29bfefb8e0..41bd9c2d7e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Oct 24 17:05:51 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/intern.h (rb_check_frozen): optimize.
+	  [ruby-core:32878]
+
 Sun Oct 24 15:16:30 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/test/unit.rb (Test::Unit::Mini#run): abort if interrupted.
diff --git a/error.c b/error.c
index 3863fb798c..b355cf890c 100644
--- a/error.c
+++ b/error.c
@@ -1589,10 +1589,11 @@ rb_error_frozen(const char *what)
     rb_raise(rb_eRuntimeError, "can't modify frozen %s", what);
 }
 
+#undef rb_check_frozen
 void
 rb_check_frozen(VALUE obj)
 {
-    if (OBJ_FROZEN(obj)) rb_error_frozen(rb_obj_classname(obj));
+    rb_check_frozen_internal(obj);
 }
 
 void
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 3f6f4a2743..b18a1f542b 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -213,6 +213,23 @@ PRINTF_ARGS(void rb_compile_error_append(const char*, ...), 1, 2);
 NORETURN(void rb_load_fail(const char*));
 NORETURN(void rb_error_frozen(const char*));
 void rb_check_frozen(VALUE);
+#define rb_check_frozen_internal(obj) do { \
+	VALUE frozen_obj = (obj); \
+	if (OBJ_FROZEN(frozen_obj)) { \
+	    rb_error_frozen(rb_obj_classname(frozen_obj)); \
+	} \
+    } while (0)
+#ifdef __GNUC__
+#define rb_check_frozen(obj) __extension__({rb_check_frozen_internal(obj);})
+#else
+static inline void
+rb_check_frozen_inline(VALUE obj)
+{
+    rb_check_frozen_internal(obj);
+}
+#define rb_check_frozen(obj) rb_check_frozen_inline(obj)
+#endif
+
 /* eval.c */
 int rb_sourceline(void);
 const char *rb_sourcefile(void);