diff --git a/Source/wall.f90 b/Source/wall.f90
index c9dd3711b4f..58260036433 100644
--- a/Source/wall.f90
+++ b/Source/wall.f90
@@ -162,10 +162,9 @@ SUBROUTINE WALL_BC(T,DT,NM)
       IF (B1%NODE_INDEX/=0) CALL CALC_HVAC_BC(BC,B1,SF)
    ENDIF
 
-   IF (WC%BOUNDARY_TYPE/=OPEN_BOUNDARY .AND. WC%BOUNDARY_TYPE/=INTERPOLATED_BOUNDARY) THEN
-      CALL CALCULATE_ZZ_F(T,DT,WALL_INDEX=IW)
-      CALL CALCULATE_RHO_F(BC,B1,WALL_INDEX=IW)
-   ENDIF
+   IF (WC%BOUNDARY_TYPE/=OPEN_BOUNDARY .AND. WC%BOUNDARY_TYPE/=INTERPOLATED_BOUNDARY) CALL CALCULATE_ZZ_F(T,DT,WALL_INDEX=IW)
+
+   IF (WC%BOUNDARY_TYPE/=INTERPOLATED_BOUNDARY) CALL CALCULATE_RHO_F(BC,B1,WALL_INDEX=IW)
 
 ENDDO WALL_CELL_LOOP
 !$OMP END DO
@@ -1496,7 +1495,7 @@ SUBROUTINE CALCULATE_RHO_F(BC,B1,WALL_INDEX,CFACE_INDEX)
 
 ! Fill exterior ghost cells with surface density and temperature
 
-IF (PRESENT(WALL_INDEX)) THEN
+IF (PRESENT(WALL_INDEX) .AND. BOUNDARY_TYPE/=OPEN_BOUNDARY) THEN
    IF (WALL_INDEX<=N_EXTERNAL_WALL_CELLS) THEN
       RHOP(BC%II ,BC%JJ, BC%KK ) = B1%RHO_F
       RHOP(BC%II2,BC%JJ2,BC%KK2) = B1%RHO_F