diff --git a/Source/dump.f90 b/Source/dump.f90
index 1fe6941244..eb4090691e 100644
--- a/Source/dump.f90
+++ b/Source/dump.f90
@@ -8206,7 +8206,7 @@ REAL(EB) RECURSIVE FUNCTION GAS_PHASE_OUTPUT(T,DT,NM,II,JJ,KK,IND,IND2,Y_INDEX,Z
 
    CASE(253)  ! ZONE PRESSURE SOLVER TYPE
       GAS_PHASE_OUTPUT_RES = REAL(PRES_FLAG,EB)
-      IF (PRES_FLAG==ULMAT_FLAG) THEN
+      IF (PRES_FLAG==ULMAT_FLAG .AND. ALLOCATED(MESHES(NM)%ZONE_MESH)) THEN
          IF (ZONE_MESH(ZONE_MESH(PRESSURE_ZONE(II,JJ,KK))%CONNECTED_ZONE_PARENT)%USE_FFT) THEN
             GAS_PHASE_OUTPUT_RES = REAL(FFT_FLAG,EB)
          ELSE
@@ -8217,7 +8217,7 @@ REAL(EB) RECURSIVE FUNCTION GAS_PHASE_OUTPUT(T,DT,NM,II,JJ,KK,IND,IND2,Y_INDEX,Z
 
    CASE(254)  ! PRESSURE ZONE PARENT
       GAS_PHASE_OUTPUT_RES = 0._EB
-      IF (PRES_FLAG==ULMAT_FLAG) THEN
+      IF (PRES_FLAG==ULMAT_FLAG .AND. ALLOCATED(MESHES(NM)%ZONE_MESH)) THEN
          GAS_PHASE_OUTPUT_RES = REAL(ZONE_MESH(PRESSURE_ZONE(II,JJ,KK))%CONNECTED_ZONE_PARENT,EB)
       ENDIF
 
diff --git a/Source/main.f90 b/Source/main.f90
index d825fe5f80..875609ba43 100644
--- a/Source/main.f90
+++ b/Source/main.f90
@@ -282,28 +282,6 @@ PROGRAM FDS
    CALL STOP_CHECK(1)
 ENDIF
 
-! Poisson solver initialization
-
-SELECT CASE(PRES_FLAG)
-   CASE(FFT_FLAG)
-      ! All solvers require INITIALIZE_POISSON_SOLVER in INITIALIZE_MESH_VARIABLES_2
-   CASE(GLMAT_FLAG,UGLMAT_FLAG)
-      CALL GLMAT_SOLVER_SETUP(1)
-      CALL STOP_CHECK(1)
-      CALL MESH_EXCHANGE(3) ! Exchange guard cell info for CCVAR(I,J,K,CGSC) -> HS.
-      CALL GLMAT_SOLVER_SETUP(2)
-      CALL MESH_EXCHANGE(3) ! Exchange guard cell info for CCVAR(I,J,K,UNKH) -> HS.
-      CALL GLMAT_SOLVER_SETUP(3)
-      CALL STOP_CHECK(1)
-   CASE(ULMAT_FLAG)
-      DO NM=LOWER_MESH_INDEX,UPPER_MESH_INDEX
-         CALL ULMAT_SOLVER_SETUP(NM)
-      ENDDO
-      CALL STOP_CHECK(1)
-END SELECT
-
-IF (MY_RANK==0 .AND. VERBOSE) CALL VERBOSE_PRINTOUT('Completed Poisson initialization')
-
 ! Initialize the flow field with random noise to eliminate false symmetries
 
 DO NM=LOWER_MESH_INDEX,UPPER_MESH_INDEX
@@ -524,7 +502,9 @@ PROGRAM FDS
 
 IF (HVAC_SOLVE .AND. N_ZONE>0 .AND. .NOT.SOLID_PHASE_ONLY) CALL EXCHANGE_DIVERGENCE_INFO
 
-CALL GLOBAL_MATRIX_REASSIGN
+CALL GLOBAL_MATRIX_REASSIGN(FORCE_REASSIGN=.TRUE.)
+
+IF (MY_RANK==0 .AND. VERBOSE) CALL VERBOSE_PRINTOUT('Completed Poisson initialization')
 
 ! Write out character strings to .smv file
 
@@ -889,7 +869,7 @@ PROGRAM FDS
 
    ! Update global pressure matrices after zone connections
 
-   CALL GLOBAL_MATRIX_REASSIGN
+   CALL GLOBAL_MATRIX_REASSIGN(FORCE_REASSIGN=.FALSE.)
 
    ! Exchange mass loss information for OBSTs abutting interpolated boundaries
 
@@ -1613,17 +1593,20 @@ END SUBROUTINE CREATE_OR_REMOVE_OBSTRUCTIONS
 !> CREATE_OR_REMOVE_OBSTRUCTIONS or CONNECTED_ZONES has been updated.  Zone connections are established
 !> in DIVERGENCE_PART_1, so global reassignment must follow.
 
-SUBROUTINE GLOBAL_MATRIX_REASSIGN
+SUBROUTINE GLOBAL_MATRIX_REASSIGN(FORCE_REASSIGN)
+
+LOGICAL, INTENT(IN) :: FORCE_REASSIGN
 
-IF (OBST_CREATED_OR_REMOVED .OR. ICYC==1) THEN
+IF (OBST_CREATED_OR_REMOVED .OR. FORCE_REASSIGN) THEN
    SELECT CASE (PRES_FLAG)
       CASE (ULMAT_FLAG)
          DO NM=LOWER_MESH_INDEX,UPPER_MESH_INDEX
-            CALL FINISH_ULMAT_SOLVER(NM)
+            IF(ALLOCATED(MESHES(NM)%ZONE_MESH)) CALL FINISH_ULMAT_SOLVER(NM)
             CALL ULMAT_SOLVER_SETUP(NM)
          ENDDO
+         CALL STOP_CHECK(1)
       CASE (UGLMAT_FLAG,GLMAT_FLAG)
-         CALL FINISH_GLMAT_SOLVER
+         IF(ALLOCATED(ZONE_SOLVE)) CALL FINISH_GLMAT_SOLVER
          CALL GLMAT_SOLVER_SETUP(1)
          CALL STOP_CHECK(1)
          CALL MESH_EXCHANGE(3) ! Exchange guard cell info for CCVAR(I,J,K,CGSC) -> HS.