diff --git a/ChangeLog b/ChangeLog
index 398e344d33..2e2d2bcfca 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Oct 31 18:17:38 2012  Narihiro Nakamura  <authornari@gmail.com>
+
+	* gc.c (gc_profile_record): don't define unused variables when
+	  GC_PROFILE_MORE_DETAIL is 0.
+
 Wed Oct 31 18:10:53 2012  Narihiro Nakamura  <authornari@gmail.com>
 
 	* gc.c (gc_prof_mark_timer_stop): count is not initialized.
diff --git a/gc.c b/gc.c
index f19a7325ff..f5411282c8 100644
--- a/gc.c
+++ b/gc.c
@@ -118,22 +118,27 @@ static ruby_gc_params_t initial_params = {
 
 typedef struct gc_profile_record {
     double gc_time;
-    double gc_mark_time;
-    double gc_sweep_time;
     double gc_invoke_time;
 
-    size_t heap_use_slots;
-    size_t heap_live_objects;
-    size_t heap_free_objects;
     size_t heap_total_objects;
     size_t heap_use_size;
     size_t heap_total_size;
 
-    int have_finalize;
     int is_marked;
 
+#if GC_PROFILE_MORE_DETAIL
+    double gc_mark_time;
+    double gc_sweep_time;
+
+    size_t heap_use_slots;
+    size_t heap_live_objects;
+    size_t heap_free_objects;
+
+    int have_finalize;
+
     size_t allocate_increase;
     size_t allocate_limit;
+#endif
 } gc_profile_record;