submitted as:
https://github.com/ceph-dovecot/dovecot-ceph-plugin/pull/275

--- a/src/librmb/rados-metadata.h
+++ b/src/librmb/rados-metadata.h
@@ -31,9 +31,9 @@
 
   RadosMetadata(enum rbox_metadata_key _key, const char* val) { convert(_key, val); }
 
-  RadosMetadata(enum rbox_metadata_key _key, const uint& val) { convert(_key, val); }
+  RadosMetadata(enum rbox_metadata_key _key, const uint32_t& val) { convert(_key, val); }
 
-  RadosMetadata(enum rbox_metadata_key _key, const size_t& val) { convert(_key, val); }
+  RadosMetadata(enum rbox_metadata_key _key, const uint64_t& val) { convert(_key, val); }
   RadosMetadata(enum rbox_metadata_key _key, const int val) { convert(_key, val); }
   ~RadosMetadata() {}
 
@@ -91,17 +91,17 @@
     bl.append(str.c_str(), str.length() + 1);
   }
 
-  void convert(enum rbox_metadata_key _key, const uint& value) {
+  void convert(enum rbox_metadata_key _key, const uint32_t& value) {
     bl.clear();
     key = librmb::rbox_metadata_key_to_char(_key);
     std::string val = std::to_string(value);
     bl.append(val.c_str(), val.length() + 1);
   }
 
-  void convert(enum rbox_metadata_key _key, const size_t& value) {
+  void convert(enum rbox_metadata_key _key, const uint64_t& value) {
     bl.clear();
     key = librmb::rbox_metadata_key_to_char(_key);
-    std::string val = std::to_string(static_cast<int>(value));
+    std::string val = std::to_string(static_cast<uint64_t>(value));
     bl.append(val.c_str(), val.length() + 1);
   }
   void convert(enum rbox_metadata_key _key, const int value) {