diff --git a/lib/std/fs/File.zig b/lib/std/fs/File.zig
index 231e7a5b7d..37d40a885a 100644
--- a/lib/std/fs/File.zig
+++ b/lib/std/fs/File.zig
@@ -1369,7 +1369,7 @@ pub const Reader = struct {
                 r.pos = offset;
             },
             .streaming, .streaming_reading => {
-                if (offset >= r.pos) return Reader.seekBy(r, offset - r.pos);
+                if (offset >= r.pos) return Reader.seekBy(r, @intCast(offset - r.pos));
                 if (r.seek_err) |err| return err;
                 posix.lseek_SET(r.file.handle, offset) catch |err| {
                     r.seek_err = err;
@@ -1657,6 +1657,7 @@ pub const Writer = struct {
             .file = w.file,
             .mode = w.mode,
             .pos = w.pos,
+            .interface = Reader.initInterface(w.interface.buffer),
             .seek_err = w.seek_err,
         };
     }