diff --git a/ChangeLog b/ChangeLog
index 9aefa55fe9..7ebd142e69 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Apr 28 17:42:42 2014  Narihiro Nakamura  <authornari@gmail.com>
+
+	* gc.c: This argument must be a pointer.
+
 Mon Apr 28 17:40:15 2014  Narihiro Nakamura  <authornari@gmail.com>
 
 	* gc.c: Fix typos. These are undefined variables.
diff --git a/gc.c b/gc.c
index ae5b634e38..49b54e8b26 100644
--- a/gc.c
+++ b/gc.c
@@ -6127,7 +6127,7 @@ objspace_malloc_increase(rb_objspace_t *objspace, void *mem, size_t new_size, si
 	    rb_bug("objspace_malloc_increase: underflow malloc_params.allocated_size.");
 	}
 #endif
-	atomic_sub_nounderflow(objspace->malloc_params.allocated_size, dec_size);
+	atomic_sub_nounderflow(&objspace->malloc_params.allocated_size, dec_size);
     }
 
     if (0) fprintf(stderr, "incraese - ptr: %p, type: %s, new_size: %d, old_size: %d\n",
@@ -6145,7 +6145,7 @@ objspace_malloc_increase(rb_objspace_t *objspace, void *mem, size_t new_size, si
 	{
 	    size_t allocations = objspace->malloc_params.allocations;
 	    if (allocations > 0) {
-		atomic_sub_nounderflow(objspace->malloc_params.allocations, 1);
+		atomic_sub_nounderflow(&objspace->malloc_params.allocations, 1);
 	    }
 #if MALLOC_ALLOCATED_SIZE_CHECK
 	    else {