diff --git a/lib/system/cellsets.nim b/lib/system/cellsets.nim
index ea00176b539fc..779f1a91ffd43 100644
--- a/lib/system/cellsets.nim
+++ b/lib/system/cellsets.nim
@@ -13,7 +13,8 @@ when defined(gcOrc) or defined(gcArc):
   type
     PCell = Cell
 
-  include bitmasks
+  when not declaredInScope(PageShift):
+    include bitmasks
 
 else:
   type