diff --git a/lib/rspec/rails/example/system_example_group.rb b/lib/rspec/rails/example/system_example_group.rb
index 57266d0a27..59c5606cca 100644
--- a/lib/rspec/rails/example/system_example_group.rb
+++ b/lib/rspec/rails/example/system_example_group.rb
@@ -114,7 +114,8 @@ def driven_by(driver, **driver_options, &blk)
             original_after_teardown.bind(self).call
           ensure
             myio = $stdout
-            RSpec.current_example.metadata[:extra_failure_lines] = myio.string
+            myio.rewind
+            RSpec.current_example.metadata[:extra_failure_lines] = myio.readlines
             $stdout = orig_stdout
           end
         end