diff --git a/packager/file/file.cc b/packager/file/file.cc
index 6c4933f6db..c0b4586e2d 100644
--- a/packager/file/file.cc
+++ b/packager/file/file.cc
@@ -27,7 +27,7 @@ DEFINE_uint64(io_cache_size,
               "Size of the threaded I/O cache, in bytes. Specify 0 to disable "
               "threaded I/O.");
 DEFINE_uint64(io_block_size,
-              2ULL << 20,
+              1ULL << 16,
               "Size of the block size used for threaded I/O, in bytes.");
 
 // Needed for Windows weirdness which somewhere defines CopyFile as CopyFileW.