1 files changed, 5 insertions, 3 deletions
diff --git a/klm/util/stream/io.cc b/klm/util/stream/io.cc
index c7ad2980..0459f706 100644
--- a/klm/util/stream/io.cc
+++ b/klm/util/stream/io.cc
@@ -29,15 +29,17 @@ void Read::Run(const ChainPosition &position) {
 void PRead::Run(const ChainPosition &position) {
   scoped_fd owner;
   if (own_) owner.reset(file_);
-  uint64_t size = SizeOrThrow(file_);
+  const uint64_t size = SizeOrThrow(file_);
   UTIL_THROW_IF(size % static_cast<uint64_t>(position.GetChain().EntrySize()), ReadSizeException, "File size " << file_ << " size is " << size << " not a multiple of " << position.GetChain().EntrySize());
-  std::size_t block_size = position.GetChain().BlockSize();
+  const std::size_t block_size = position.GetChain().BlockSize();
+  const uint64_t block_size64 = static_cast<uint64_t>(block_size);
   Link link(position);
   uint64_t offset = 0;
-  for (; offset + block_size < size; offset += block_size, ++link) {
+  for (; offset + block_size64 < size; offset += block_size64, ++link) {
     PReadOrThrow(file_, link->Get(), block_size, offset);
     link->SetValidSize(block_size);
   }
+  // size - offset is <= block_size, so it casts to 32-bit fine.
   if (size - offset) {
     PReadOrThrow(file_, link->Get(), size - offset, offset);
     link->SetValidSize(size - offset);