diff --git a/ProcessLib/PhaseField/Tests.cmake b/ProcessLib/PhaseField/Tests.cmake
index cfde361af85..8567d4eeb29 100644
--- a/ProcessLib/PhaseField/Tests.cmake
+++ b/ProcessLib/PhaseField/Tests.cmake
@@ -146,9 +146,9 @@ AddTest(
 
 if(OGS_USE_PETSC)
     NotebookTest(NOTEBOOKFILE PhaseField/surfing_jupyter_notebook/surfing_pyvista.ipynb RUNTIME 25)
-    NotebookTest(NOTEBOOKFILE PhaseField/beam_jupyter_notebook/beam.ipynb RUNTIME 500 PROPERTIES PROCESSORS 3)
-    NotebookTest(NOTEBOOKFILE PhaseField/tpb_jupyter_notebook/TPB.ipynb RUNTIME 110 PROPERTIES PROCESSORS 4)
+    NotebookTest(NOTEBOOKFILE PhaseField/beam_jupyter_notebook/beam.ipynb RUNTIME 500 PROPERTIES PROCESSORS 3 RUN_SERIAL TRUE)
+    NotebookTest(NOTEBOOKFILE PhaseField/tpb_jupyter_notebook/TPB.ipynb RUNTIME 110 PROPERTIES PROCESSORS 4 RUN_SERIAL TRUE)
     NotebookTest(NOTEBOOKFILE PhaseField/kregime_jupyter_notebook/Kregime_Static_jupyter.ipynb RUNTIME 40)
-    NotebookTest(NOTEBOOKFILE PhaseField/PForthotropy_jupyter_notebook/sen_shear.ipynb RUNTIME 500 PROPERTIES PROCESSORS 4)
+    NotebookTest(NOTEBOOKFILE PhaseField/PForthotropy_jupyter_notebook/sen_shear.ipynb RUNTIME 500 PROPERTIES PROCESSORS 4 RUN_SERIAL TRUE)
     NotebookTest(NOTEBOOKFILE PhaseField/Kregime_Propagating_jupyter_notebook/Kregime_Propagating_jupyter.ipynb RUNTIME 550)
 endif()