diff --git a/src/heap.cpp b/src/heap.cpp
index c8f30c0369..e441640364 100644
--- a/src/heap.cpp
+++ b/src/heap.cpp
@@ -544,9 +544,9 @@ class Fixie {
   // you add/remove/change fields in this class:
 
   uint8_t age;
-  bool hasMask;
-  bool marked;
-  bool dirty;
+  uint8_t hasMask;
+  uint8_t marked;
+  uint8_t dirty;
   uint32_t size;
   Fixie* next;
   Fixie** handle;