diff --git a/ChangeLog b/ChangeLog
index ffceb1a99b..eadbae7731 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Jan 26 07:57:28 2016  Joseph Tibbertsma  <josephtibbertsma@gmail.com>
+
+	* gc.c (RVALUE_PAGE_WB_UNPROTECTED): fix a typo of argument name.
+	  [Fix GH-1221]
+
 Mon Jan 25 17:26:54 2016  Eric Wong  <e@80x24.org>
 
 	* ruby_assert.h (RUBY_ASSERT_WHEN): fix reference to macro name
diff --git a/gc.c b/gc.c
index f75a489ba5..9adb384a16 100644
--- a/gc.c
+++ b/gc.c
@@ -973,7 +973,7 @@ tick(void)
 #define RVALUE_UNCOLLECTIBLE_BITMAP(obj)  MARKED_IN_BITMAP(GET_HEAP_UNCOLLECTIBLE_BITS(obj), (obj))
 #define RVALUE_MARKING_BITMAP(obj)        MARKED_IN_BITMAP(GET_HEAP_MARKING_BITS(obj), (obj))
 
-#define RVALUE_PAGE_WB_UNPROTECTED(apge, obj) MARKED_IN_BITMAP((page)->wb_unprotected_bits, (obj))
+#define RVALUE_PAGE_WB_UNPROTECTED(page, obj) MARKED_IN_BITMAP((page)->wb_unprotected_bits, (obj))
 #define RVALUE_PAGE_UNCOLLECTIBLE(page, obj)  MARKED_IN_BITMAP((page)->uncollectible_bits, (obj))
 #define RVALUE_PAGE_MARKING(page, obj)        MARKED_IN_BITMAP((page)->marking_bits, (obj))