diff --git a/CMakeLists.txt b/CMakeLists.txt
index f9af1f2cf..85a5c5bbf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -65,9 +65,9 @@ find_package(nlohmann_json 3.10.5)
 
 add_subdirectory(edm4hep)
 add_subdirectory(utils)
-add_subdirectory(test)
 add_subdirectory(tools)
 add_subdirectory(python)
+add_subdirectory(test)
 
 #--- create uninstall target ---------------------------------------------------
 include(cmake/EDM4HEPUninstall.cmake)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d6af4fc67..58b580ea5 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -114,3 +114,13 @@ endif()
 
 add_subdirectory(utils)
 add_subdirectory(tools)
+
+
+include(ExternalData)
+list(APPEND ExternalData_URL_TEMPLATES
+  "https://key4hep.web.cern.ch:443/testFiles/EDM4hep/%(hash)"
+)
+
+add_subdirectory(backwards_compat)
+
+ExternalData_Add_Target(backward_compat_tests)
diff --git a/test/backwards_compat/CMakeLists.txt b/test/backwards_compat/CMakeLists.txt
new file mode 100644
index 000000000..7edfb00c5
--- /dev/null
+++ b/test/backwards_compat/CMakeLists.txt
@@ -0,0 +1,15 @@
+ExternalData_Add_Test(backward_compat_tests
+  NAME backwards_compat_v00-99 COMMAND pytest --inputfile=DATA{${CMAKE_CURRENT_SOURCE_DIR}/input_files/edm4hep_example_v00-99_podio_v01-00-01.root})
+set_test_env(backwards_compat_v00-99)
+
+ExternalData_Add_Test(backward_compat_tests
+  NAME backwards_compat_rntuple_v00-99 COMMAND pytest --inputfile=DATA{${CMAKE_CURRENT_SOURCE_DIR}/input_files/edm4hep_example_rntuple_v00-99_podio_v01-00-01.root})
+set_test_env(backwards_compat_rntuple_v00-99)
+
+set_tests_properties(
+  backwards_compat_v00-99
+  backwards_compat_rntuple_v00-99
+
+  PROPERTIES
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/test
+)
diff --git a/test/backwards_compat/input_files/edm4hep_example_rntuple_v00-99_podio_v01-00-01.root.md5 b/test/backwards_compat/input_files/edm4hep_example_rntuple_v00-99_podio_v01-00-01.root.md5
new file mode 100644
index 000000000..053830daa
--- /dev/null
+++ b/test/backwards_compat/input_files/edm4hep_example_rntuple_v00-99_podio_v01-00-01.root.md5
@@ -0,0 +1 @@
+6f3e8c366c7014c2220acd94e2cd4558
diff --git a/test/backwards_compat/input_files/edm4hep_example_v00-99_podio_v01-00-01.root.md5 b/test/backwards_compat/input_files/edm4hep_example_v00-99_podio_v01-00-01.root.md5
new file mode 100644
index 000000000..58b17ba0e
--- /dev/null
+++ b/test/backwards_compat/input_files/edm4hep_example_v00-99_podio_v01-00-01.root.md5
@@ -0,0 +1 @@
+215f4db666f696e5f9ad010cc1001b05