diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index ce91314f2c0c9ebde82e0dc98c1fc680ab73d774..8fee6789fae2dbc3d95af7ec14ca26014f6d29bf 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -756,8 +756,8 @@ static int gen8_ppgtt_alloc_page_directories(struct i915_hw_ppgtt *ppgtt,
 
 	WARN_ON(!bitmap_empty(new_pds, GEN8_LEGACY_PDPES));
 
-	/* FIXME: PPGTT container_of won't work for 64b */
-	WARN_ON((start + length) > 0x800000000ULL);
+	/* FIXME: upper bound must not overflow 32 bits  */
+	WARN_ON((start + length) >= (1ULL << 32));
 
 	gen8_for_each_pdpe(pd, pdp, start, length, temp, pdpe) {
 		if (pd)