diff --git a/spec/delayed/backend/test.rb b/lib/delayed/backend/test.rb
similarity index 100%
rename from spec/delayed/backend/test.rb
rename to lib/delayed/backend/test.rb
diff --git a/lib/delayed/serialization/test.rb b/lib/delayed/serialization/test.rb
new file mode 100644
index 000000000..a5c2e8105
--- /dev/null
+++ b/lib/delayed/serialization/test.rb
@@ -0,0 +1 @@
+# This empty file is required when :test backend is used.
diff --git a/spec/delayed/serialization/test.rb b/spec/delayed/serialization/test.rb
deleted file mode 100644
index e69de29bb..000000000