diff --git a/bin/base64.c b/bin/base64.c
index 90a589e..f411369 100644
--- a/bin/base64.c
+++ b/bin/base64.c
@@ -3,6 +3,11 @@
 #  define MINGW
 #endif
 
+// Test for Windows.
+#if defined(_WIN32) || defined(_WIN64)
+#  define WIN
+#endif
+
 // Decide if the writev(2) system call needs to be emulated as a series of
 // write(2) calls. At least MinGW does not support writev(2).
 #ifdef MINGW
@@ -24,6 +29,12 @@
 #include <errno.h>
 #include <limits.h>
 
+// Include Windows-specific headers.
+#ifdef WIN
+#  include <io.h>
+#  include <fcntl.h>
+#endif
+
 #include "../include/libbase64.h"
 
 // Size of the buffer for the "raw" (not base64-encoded) data in bytes.
@@ -308,6 +319,15 @@ encode (const struct config *config, struct buffer *buf)
 	size_t nread, nout;
 	struct base64_state state;
 
+#ifdef WIN
+
+	// On Windows platforms, ensure that stdout is binary-clean, and
+	// newlines at the end of the line are not silently converted to CRLFs.
+	// This seems to be the portable way to do it. freopen() and
+	// SetConsoleMode() occasionally result in permission errors.
+	_setmode(1, _O_BINARY);
+#endif
+
 	// Initialize the encoder's state structure.
 	base64_stream_encode_init(&state, 0);