diff --git a/cmake/modules/DuneMPI.cmake b/cmake/modules/DuneMPI.cmake
index 3d7f1107b10fc4e710b252f7e6716110a1006681..f6ca504d500593eae263483c358d8d550e731920 100644
--- a/cmake/modules/DuneMPI.cmake
+++ b/cmake/modules/DuneMPI.cmake
@@ -58,7 +58,7 @@ function(add_dune_mpi_flags)
     set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND PROPERTY COMPILE_DEFINITIONS ENABLE_MPI=1
       MPICH_SKIP_MPICXX MPIPP_H)
     if(NOT (ADD_MPI_SOURCE_ONLY OR ADD_MPI_OBJECT))
-    set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND PROPERTY LINK_FLAGS ${MPI_DUNE_LINK_FLAGS})
+    set_property(${_prefix} ${ADD_MPI_UNPARSED_ARGUMENTS} APPEND_STRING PROPERTY LINK_FLAGS ${MPI_DUNE_LINK_FLAGS})
     foreach(target ${ADD_MPI_UNPARSED_ARGUMENTS})
       target_link_libraries(${target} ${MPI_DUNE_LIBRARIES})
     endforeach(target ${ADD_MPI_UNPARSED_ARGUMENTS})