diff --git a/src/tools/rbd_mirror/InstanceReplayer.cc b/src/tools/rbd_mirror/InstanceReplayer.cc
index 097007231b..52e60605c7 100644
--- a/src/tools/rbd_mirror/InstanceReplayer.cc
+++ b/src/tools/rbd_mirror/InstanceReplayer.cc
@@ -372,9 +372,9 @@
     return;
   }
 
-  size_t image_count = 0;
-  size_t warning_count = 0;
-  size_t error_count = 0;
+  uint64_t image_count = 0;
+  uint64_t warning_count = 0;
+  uint64_t error_count = 0;
   for (auto &it : m_image_replayers) {
     ++image_count;
     auto health_state = it.second->get_health_state();
diff --git a/src/tools/rbd_mirror/PoolWatcher.h b/src/tools/rbd_mirror/PoolWatcher.h
index 51ee00e9ad..9a02bad4bd 100644
--- a/src/tools/rbd_mirror/PoolWatcher.h
+++ b/src/tools/rbd_mirror/PoolWatcher.h
@@ -52,7 +52,7 @@ public:
   void init(Context *on_finish = nullptr);
   void shut_down(Context *on_finish);
 
-  inline size_t get_image_count() const {
+  inline uint64_t get_image_count() const {
     Mutex::Locker locker(m_lock);
     return m_image_ids.size();
   }