diff --git a/ChangeLog b/ChangeLog
index 19f8978a17..98e8b088fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Jul 10 20:47:51 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* internal.h (STATIC_ASSERT): move from enum.c.
+
 Wed Jul 10 20:08:21 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (SIZEOF_BDIGIT_DBL): Add a ifdef guard for test.
diff --git a/enum.c b/enum.c
index a3cefe735f..8dd24514b5 100644
--- a/enum.c
+++ b/enum.c
@@ -15,8 +15,6 @@
 #include "id.h"
 #include "internal.h"
 
-#define STATIC_ASSERT(name, expr) typedef int static_assert_##name##_check[1 - 2*!(expr)]
-
 VALUE rb_f_send(int argc, VALUE *argv, VALUE recv);
 
 VALUE rb_mEnumerable;
diff --git a/internal.h b/internal.h
index dd4d182a21..22600da9e6 100644
--- a/internal.h
+++ b/internal.h
@@ -21,6 +21,8 @@ extern "C" {
 
 #define numberof(array) ((int)(sizeof(array) / sizeof((array)[0])))
 
+#define STATIC_ASSERT(name, expr) typedef int static_assert_##name##_check[1 - 2*!(expr)]
+
 #define GCC_VERSION_SINCE(major, minor, patchlevel) \
   (defined(__GNUC__) && !defined(__INTEL_COMPILER) && \
    ((__GNUC__ > (major)) ||  \