diff --git a/.gitmodules b/.gitmodules
index 7d85724fadf9688055e5b7b9009885fad793dbd1..8021c5e26d8d9d95504d93e6dd540d5967e0f09d 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -16,6 +16,7 @@
 [submodule "Tests/Data"]
 	path = Tests/Data
 	url = https://github.com/ufz/ogs-data
+	shallow = true
 [submodule "ThirdParty/vtkGUISupportQt"]
 	path = ThirdParty/vtkGUISupportQt
 	url = https://github.com/ufz/vtkGUISupportQt.git