diff --git a/test/io/CMakeLists.txt b/test/io/CMakeLists.txt
index b129432a70ecc4053a5f691d1707214484040272..4aa65aa7350f5d760ef2db954ac49cf62896191f 100644
--- a/test/io/CMakeLists.txt
+++ b/test/io/CMakeLists.txt
@@ -20,6 +20,6 @@ dumux_add_test(
     NAME test_grid_writer_parallel
     SOURCES test_grid_writer_parallel.cc
     CMAKE_GUARD DUMUX_HAVE_GRIDFORMAT
-    MPI_RANKS 2
+    MPI_RANKS 1 2
     TIMEOUT 100
 )