diff --git a/src/pflotran/general.F90 b/src/pflotran/general.F90
index 26cb3693f..d38ab4ccc 100644
--- a/src/pflotran/general.F90
+++ b/src/pflotran/general.F90
@@ -1055,7 +1055,7 @@ subroutine GeneralResidual(snes,xx,r,realization,ierr)
   PetscViewer :: viewer
   PetscErrorCode :: ierr
   
-  Mat, parameter :: null_mat = tMat(-1)
+  Mat, parameter :: null_mat = tMat(0)
   type(discretization_type), pointer :: discretization
   type(grid_type), pointer :: grid
   type(patch_type), pointer :: patch
@@ -1499,7 +1499,7 @@ subroutine GeneralJacobian(snes,xx,A,B,realization,ierr)
   PetscInt :: irow
   PetscInt :: local_id_up, local_id_dn
   PetscInt :: ghosted_id_up, ghosted_id_dn
-  Vec, parameter :: null_vec = tVec(-1)
+  Vec, parameter :: null_vec = tVec(0)
   
   PetscReal :: Jup(realization%option%nflowdof,realization%option%nflowdof), &
                Jdn(realization%option%nflowdof,realization%option%nflowdof)
diff --git a/src/pflotran/richards.F90 b/src/pflotran/richards.F90
index 51ba71961..f74cb664f 100644
--- a/src/pflotran/richards.F90
+++ b/src/pflotran/richards.F90
@@ -1774,7 +1774,7 @@ subroutine RichardsResidualSourceSink(r,realization,ierr)
   PetscReal :: well_inj_water
   PetscReal :: Dq, dphi, v_darcy, ukvr
 
-  Mat, parameter :: null_mat = tMat(-1)
+  Mat, parameter :: null_mat = tMat(0)
 
   PetscErrorCode :: ierr
 
@@ -2691,7 +2691,7 @@ subroutine RichardsJacobianSourceSink(A,realization,ierr)
   PetscReal :: pressure_max
   PetscReal :: pressure_min
   PetscReal :: ukvr, Dq, dphi, v_darcy
-  Vec, parameter :: null_vec = tVec(-1)
+  Vec, parameter :: null_vec = tVec(0)
   character(len=MAXSTRINGLENGTH) :: string
 
   patch => realization%patch
diff --git a/src/pflotran/wipp_flow.F90 b/src/pflotran/wipp_flow.F90
index a40c99fb8..85f0cc7bd 100644
--- a/src/pflotran/wipp_flow.F90
+++ b/src/pflotran/wipp_flow.F90
@@ -903,7 +903,7 @@ subroutine WIPPFloResidual(snes,xx,r,realization,pmwss_ptr,ierr)
   class(pm_wipp_srcsink_type), pointer :: pmwss_ptr
   PetscErrorCode :: ierr
   
-  Mat, parameter :: null_mat = tMat(-1)
+  Mat, parameter :: null_mat = tMat(0)
   type(discretization_type), pointer :: discretization
   type(grid_type), pointer :: grid
   type(patch_type), pointer :: patch
@@ -1370,7 +1370,7 @@ subroutine WIPPFloJacobian(snes,xx,A,B,realization,pmwss_ptr,ierr)
   PetscInt :: local_id, ghosted_id, natural_id
   PetscInt :: local_id_up, local_id_dn
   PetscInt :: ghosted_id_up, ghosted_id_dn
-  Vec, parameter :: null_vec = tVec(-1)
+  Vec, parameter :: null_vec = tVec(0)
   
   PetscReal :: Jup(realization%option%nflowdof,realization%option%nflowdof), &
                Jdn(realization%option%nflowdof,realization%option%nflowdof)