diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 096205a1630..00881854912 100644
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -215,7 +215,7 @@ public:
 	boost::intrusive::list_member_hook<>,
 	&Buffer::state_item> > state_list_t;
 
-    mempool::bluestore_meta_other::map<uint64_t, std::unique_ptr<Buffer>>
+    mempool::bluestore_meta_other::map<uint32_t, std::unique_ptr<Buffer>>
       buffer_map;
     Cache *cache;
 
@@ -250,7 +250,7 @@ public:
     void _rm_buffer(Buffer *b) {
       _rm_buffer(buffer_map.find(b->offset));
     }
-    void _rm_buffer(map<uint64_t,std::unique_ptr<Buffer>>::iterator p) {
+    void _rm_buffer(map<uint32_t,std::unique_ptr<Buffer>>::iterator p) {
       assert(p != buffer_map.end());
       cache->_audit("_rm_buffer start");
       if (p->second->is_writing()) {
@@ -262,7 +262,7 @@ public:
       cache->_audit("_rm_buffer end");
     }
 
-    map<uint64_t,std::unique_ptr<Buffer>>::iterator _data_lower_bound(
+    map<uint32_t,std::unique_ptr<Buffer>>::iterator _data_lower_bound(
       uint64_t offset) {
       auto i = buffer_map.lower_bound(offset);
       if (i != buffer_map.begin()) {