diff --git a/activesupport/lib/active_support/cache/file_store.rb b/activesupport/lib/active_support/cache/file_store.rb
index 1971ff182e..34456a594f 100644
--- a/activesupport/lib/active_support/cache/file_store.rb
+++ b/activesupport/lib/active_support/cache/file_store.rb
@@ -138,14 +138,6 @@ module ActiveSupport
           File.join(cache_path, DIR_FORMATTER % dir_1, DIR_FORMATTER % dir_2, *fname_paths)
         end
 
-        def key_file_path(key)
-          ActiveSupport::Deprecation.warn(<<-MESSAGE.strip_heredoc)
-            `key_file_path` is deprecated and will be removed from Rails 5.1.
-            Please use `normalize_key` which will return a fully resolved key or nothing.
-          MESSAGE
-          key
-        end
-
         # Translate a file path into a key.
         def file_path_key(path)
           fname = path[cache_path.to_s.size..-1].split(File::SEPARATOR, 4).last
diff --git a/activesupport/test/caching_test.rb b/activesupport/test/caching_test.rb
index f489ded1be..02a9e5eff5 100644
--- a/activesupport/test/caching_test.rb
+++ b/activesupport/test/caching_test.rb
@@ -918,12 +918,6 @@ class FileStoreTest < ActiveSupport::TestCase
     @cache.write(1, nil)
     assert_equal false, @cache.write(1, "aaaaaaaaaa", unless_exist: true)
   end
-
-  def test_can_call_deprecated_key_file_path
-    assert_deprecated "`key_file_path` is deprecated" do
-      assert_equal 111, @cache.send(:key_file_path, 111)
-    end
-  end
 end
 
 class MemoryStoreTest < ActiveSupport::TestCase