diff --git a/ChangeLog b/ChangeLog
index 513a6304da..e5d8408ddb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,11 @@
+Tue Oct 27 12:30:16 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.h (SET_MACHINE_STACK_END): use __i386__ instead of __i386,
+	  and explicit size qualifiers.
+
 Tue Oct 27 09:40:55 2009  NARUSE, Yui  <naruse@ruby-lang.org>
 
-	* gc.c (SET_MACHINE_STACK_END): add x86_64 version by nobu.
+	* gc.h (SET_MACHINE_STACK_END): add x86_64 version by nobu.
 
 Tue Oct 27 09:27:59 2009  NARUSE, Yui  <naruse@ruby-lang.org>
 
diff --git a/gc.h b/gc.h
index 42ea4a8356..0bb70c5954 100644
--- a/gc.h
+++ b/gc.h
@@ -3,9 +3,9 @@
 #define RUBY_GC_H 1
 
 #if defined(__x86_64__) && defined(__GNUC__)
-#define SET_MACHINE_STACK_END(p) __asm__("mov %%rsp, %0" : "=r" (*p))
-#elif defined(__i386) && defined(__GNUC__)
-#define SET_MACHINE_STACK_END(p) __asm__("mov %%esp, %0" : "=r" (*p))
+#define SET_MACHINE_STACK_END(p) __asm__("movq\t%%rsp, %0" : "=r" (*p))
+#elif defined(__i386__) && defined(__GNUC__)
+#define SET_MACHINE_STACK_END(p) __asm__("movl\t%%esp, %0" : "=r" (*p))
 #else
 NOINLINE(void rb_gc_set_stack_end(VALUE **stack_end_p));
 #define SET_MACHINE_STACK_END(p) rb_gc_set_stack_end(p)