diff --git a/scripts/cmake/SubmoduleSetup.cmake b/scripts/cmake/SubmoduleSetup.cmake
index 711d973da4bbd01acf886f0ec4ce9f92434c3286..6e791556cf1505fdcb5340ea0d34d9712ee841e7 100644
--- a/scripts/cmake/SubmoduleSetup.cmake
+++ b/scripts/cmake/SubmoduleSetup.cmake
@@ -1,5 +1,8 @@
 # This file initializes the required submodules
 OPTION(OGS_ADDITIONAL_SUBMODULES_TO_CHECKOUT "User given submodules which should be checked out by CMake." "")
+IF(NOT OGS_ADDITIONAL_SUBMODULES_TO_CHECKOUT)
+	SET(OGS_ADDITIONAL_SUBMODULES_TO_CHECKOUT "")
+ENDIF()
 SET(REQUIRED_SUBMODULES
 	ThirdParty/quickcheck
 	${OGS_ADDITIONAL_SUBMODULES_TO_CHECKOUT}