diff --git a/std/os.zig b/std/os.zig
index bc9d0ad4d2..fe97c1aa61 100644
--- a/std/os.zig
+++ b/std/os.zig
@@ -1136,13 +1136,14 @@ pub fn copyFile(source_path: []const u8, dest_path: []const u8) !void {
     defer in_file.close();
 
     const mode = try in_file.mode();
+    const in_stream = &in_file.inStream().stream;
 
     var atomic_file = try AtomicFile.init(dest_path, mode);
     defer atomic_file.deinit();
 
     var buf: [page_size]u8 = undefined;
     while (true) {
-        const amt = try in_file.readFull(buf[0..]);
+        const amt = try in_stream.readFull(buf[0..]);
         try atomic_file.file.write(buf[0..amt]);
         if (amt != buf.len) {
             return atomic_file.finish();