diff --git a/lib/fluent/plugin/buffer/chunk.rb b/lib/fluent/plugin/buffer/chunk.rb
index a5a6f2d3b1..d33bb1623e 100644
--- a/lib/fluent/plugin/buffer/chunk.rb
+++ b/lib/fluent/plugin/buffer/chunk.rb
@@ -206,7 +206,7 @@ def open(**kwargs, &block)
                 output_io = if chunk_io.is_a?(StringIO)
                               StringIO.new
                             else
-                              Tempfile.new('decompressed-data')
+                              Tempfile.new('decompressed-data').binmode
                             end
                 decompress(input_io: chunk_io, output_io: output_io)
                 output_io.seek(0, IO::SEEK_SET)