diff --git a/CMakeLists.txt b/CMakeLists.txt
index c8523e8f2078c43769bb82afc9e406639a4dec97..afc39bb68171c04e64c70010878655b13e48aca1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -182,7 +182,10 @@ if(OGS_USE_MPI)
 endif()
 
 # Eigen
-add_definitions(-DEIGEN_INITIALIZE_MATRICES_BY_ZERO) # TODO check if needed
+if(CMAKE_BUILD_TYPE STREQUAL "Debug")
+    add_definitions(-DEIGEN_INITIALIZE_MATRICES_BY_NAN)
+endif()
+
 if (EIGEN_NO_DEBUG)
     add_definitions(-DEIGEN_NO_DEBUG)
 endif()