diff --git a/test/run_convert.cxx b/test/run_convert.cxx
index 24d64c462..b7a687c03 100644
--- a/test/run_convert.cxx
+++ b/test/run_convert.cxx
@@ -106,6 +106,9 @@ static void
 RunConvert(PcmConvert &convert, size_t in_frame_size,
 	   FileDescriptor in_fd, FileDescriptor out_fd)
 {
+	in_fd.SetBinaryMode();
+	out_fd.SetBinaryMode();
+
 	StaticFifoBuffer<std::byte, 4096> buffer;
 
 	while (true) {
diff --git a/test/run_input.cxx b/test/run_input.cxx
index 0607dd3c6..6c2f360a3 100644
--- a/test/run_input.cxx
+++ b/test/run_input.cxx
@@ -164,6 +164,8 @@ static int
 dump_input_stream(InputStream &is, FileDescriptor out,
 		  offset_type seek, size_t chunk_size)
 {
+	out.SetBinaryMode();
+
 	std::unique_lock<Mutex> lock(is.mutex);
 
 	if (seek > 0)
diff --git a/test/run_output.cxx b/test/run_output.cxx
index 4fd3ff2ea..6d917600d 100644
--- a/test/run_output.cxx
+++ b/test/run_output.cxx
@@ -117,6 +117,8 @@ static void
 RunOutput(AudioOutput &ao, AudioFormat audio_format,
 	  FileDescriptor in_fd)
 {
+	in_fd.SetBinaryMode();
+
 	/* open the audio output */
 
 	ao.Enable();