diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 2958d08210be0bb7baa6d8147769685c1b2d70f1..c26fc76515f85465a6fd3187c132e02d645ccb9a 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -752,7 +752,7 @@ def set_fixture_class(class_names = {})
       def fixtures(*fixture_set_names)
         if fixture_set_names.first == :all
           fixture_set_names = Dir["#{fixture_path}/**/*.{yml}"]
-          fixture_set_names.map! { |f| f[(fixture_path.size + 1)..-5] }
+          fixture_set_names.map! { |f| f[(fixture_path.to_s.size + 1)..-5] }
         else
           fixture_set_names = fixture_set_names.flatten.map { |n| n.to_s }
         end
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index 8ad40ec3f4b5830b1131e2e851336e894da832b0..f6cfee0cb8455213d36f7b19e12a3b1165ca2d8c 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -576,6 +576,15 @@ def test_all_there
   end
 end
 
+class LoadAllFixturesWithPathnameTest < ActiveRecord::TestCase
+  self.fixture_path = Pathname.new(FIXTURES_ROOT).join('all')
+  fixtures :all
+
+  def test_all_there
+    assert_equal %w(developers people tasks), fixture_table_names.sort
+  end
+end
+
 class FasterFixturesTest < ActiveRecord::TestCase
   fixtures :categories, :authors