diff --git a/spec/acceptance/stores/mem_cache_store_spec.rb b/spec/acceptance/stores/mem_cache_store_spec.rb
index 2ee8832..d8684bd 100644
--- a/spec/acceptance/stores/mem_cache_store_spec.rb
+++ b/spec/acceptance/stores/mem_cache_store_spec.rb
@@ -1,6 +1,8 @@
 require_relative "../../spec_helper"
 require_relative "../../support/cache_store_helper"
 
+require "timecop"
+
 describe "MemCacheStore as a cache backend" do
   before do
     Rack::Attack.cache.store = ActiveSupport::Cache::MemCacheStore.new
@@ -11,4 +13,26 @@ describe "MemCacheStore as a cache backend" do
   end
 
   it_works_for_cache_backed_features
+
+  it "doesn't leak keys" do
+    Rack::Attack.throttle("by ip", limit: 1, period: 1) do |request|
+      request.ip
+    end
+
+    key = nil
+
+    # Freeze time during these statement to be sure that the key used by rack attack is the same
+    # we pre-calculate in local variable `key`
+    Timecop.freeze do
+      key = "rack::attack:#{Time.now.to_i}:by ip:1.2.3.4"
+
+      get "/", {}, "REMOTE_ADDR" => "1.2.3.4"
+    end
+
+    assert_equal "1", Rack::Attack.cache.store.get(key)
+
+    sleep 2.1
+
+    assert_nil Rack::Attack.cache.store.get(key)
+  end
 end