diff --git a/payload_consumer/filesystem_verifier_action.cc b/payload_consumer/filesystem_verifier_action.cc
index 2e2f6b9..4990358 100644
--- a/payload_consumer/filesystem_verifier_action.cc
+++ b/payload_consumer/filesystem_verifier_action.cc
@@ -112,7 +112,7 @@
   std::partial_sum(partition_weight_.begin(),
                    partition_weight_.end(),
                    partition_weight_.begin(),
-                   std::plus<size_t>());
+                   std::plus<uint64_t>());
 
   install_plan_.Dump();
   // If we are not writing verity, just map all partitions once at the
diff --git a/payload_consumer/filesystem_verifier_action.h b/payload_consumer/filesystem_verifier_action.h
index d8cb902..2adf62e 100644
--- a/payload_consumer/filesystem_verifier_action.h
+++ b/payload_consumer/filesystem_verifier_action.h
@@ -176,7 +176,7 @@
   // Cumulative sum of partition sizes. Used for progress report.
   // This vector will always start with 0, and end with total size of all
   // partitions.
-  std::vector<size_t> partition_weight_;
+  std::vector<uint64_t> partition_weight_;
 
   DISALLOW_COPY_AND_ASSIGN(FilesystemVerifierAction);
 };