diff --git a/src/unix2db.zig b/src/unix2db.zig
index af3d55b..761b06b 100644
--- a/src/unix2db.zig
+++ b/src/unix2db.zig
@@ -79,14 +79,16 @@ fn execute(
         return fail(errc.wrapf("open '{s}'", .{groupFname}), stderr, err);
     defer groupFile.close();
 
-    var users = User.fromReader(allocator, &errc, passwdFile.reader()) catch |err|
+    var passwdReader = io.bufferedReader(passwdFile.reader()).reader();
+    var users = User.fromReader(allocator, &errc, passwdReader) catch |err|
         return fail(errc.wrap("read users"), stderr, err);
     defer {
         for (users) |*user| user.deinit(allocator);
         allocator.free(users);
     }
 
-    var groups = Group.fromReader(allocator, groupFile.reader()) catch |err|
+    var groupReader = io.bufferedReader(groupFile.reader()).reader();
+    var groups = Group.fromReader(allocator, groupReader) catch |err|
         return fail(errc.wrap("read groups"), stderr, err);
     defer {
         for (groups) |*group| group.deinit(allocator);