diff --git a/lib/rackstash/flows.rb b/lib/rackstash/flows.rb
index 060f989..171f837 100644
--- a/lib/rackstash/flows.rb
+++ b/lib/rackstash/flows.rb
@@ -200,7 +200,7 @@ module Rackstash
     #   `Hash`.
     # @return [Hash, nil] the flushed event or `nil` if nothing was flushed
     def auto_flush(event = nil)
-      flows = to_a.select!(&:auto_flush?)
+      flows = to_a.keep_if(&:auto_flush?)
       return unless flows.any?
 
       event ||= yield if block_given?
diff --git a/spec/rackstash/flows_spec.rb b/spec/rackstash/flows_spec.rb
index 387e523..ce6e604 100644
--- a/spec/rackstash/flows_spec.rb
+++ b/spec/rackstash/flows_spec.rb
@@ -435,5 +435,13 @@ RSpec.describe Rackstash::Flows do
       expect(flows.auto_flush('foo' => 'bar')).to be_nil
       expect { |b| flows.auto_flush(&b) }.not_to yield_control
     end
+
+    it 'writes to all flows if they are all auto_flushing' do
+      auto_flush_flow = a_flow(auto_flush: true)
+      expect(auto_flush_flow).to receive(:write).with('foo' => 'bar')
+      flows << auto_flush_flow
+
+      flows.auto_flush('foo' => 'bar')
+    end
   end
 end