diff --git a/io/sys/darwin/file.c b/io/sys/darwin/file.c
index 3cb757f..6ae029d 100644
--- a/io/sys/darwin/file.c
+++ b/io/sys/darwin/file.c
@@ -18,9 +18,8 @@
 
 static enum b_status stream_close(b_stream *);
 static enum b_status stream_getc(b_stream *, int *);
-static enum b_status stream_read(b_stream *, unsigned char *, size_t, size_t *);
-static enum b_status stream_write(
-	b_stream *, const unsigned char *, size_t, size_t *);
+static enum b_status stream_read(b_stream *, void *, size_t, size_t *);
+static enum b_status stream_write(b_stream *, const void *, size_t, size_t *);
 static enum b_status stream_seek(b_stream *, long long, b_stream_seek_origin);
 static enum b_status stream_tell(const b_stream *, size_t *);
 
@@ -315,7 +314,7 @@ static enum b_status stream_getc(b_stream *stream, int *out)
 }
 
 static enum b_status stream_read(
-	b_stream *stream, unsigned char *buf, size_t max, size_t *nr_read)
+	b_stream *stream, void *buf, size_t max, size_t *nr_read)
 {
 	struct b_file_p *file = b_object_get_private(stream, B_TYPE_FILE);
 
@@ -326,7 +325,7 @@ static enum b_status stream_read(
 }
 
 static enum b_status stream_write(
-	b_stream *stream, const unsigned char *buf, size_t count, size_t *nr_written)
+	b_stream *stream, const void *buf, size_t count, size_t *nr_written)
 {
 	struct b_file_p *file = b_object_get_private(stream, B_TYPE_FILE);