diff --git a/ortools/constraint_solver/csharp/CMakeLists.txt b/ortools/constraint_solver/csharp/CMakeLists.txt
index 7a7edf5642..44fd096092 100644
--- a/ortools/constraint_solver/csharp/CMakeLists.txt
+++ b/ortools/constraint_solver/csharp/CMakeLists.txt
@@ -1,7 +1,6 @@
 set_property(SOURCE routing.i PROPERTY CPLUSPLUS ON)
 set_property(SOURCE routing.i PROPERTY SWIG_MODULE_NAME operations_research_constraint_solver)
 set_property(SOURCE routing.i PROPERTY COMPILE_OPTIONS
-  -nofastunpack
   -namespace ${OR_TOOLS_DOTNET}.ConstraintSolver
   -dllimport google-ortools-native
   )