diff --git a/src/MNH/ch_f77.fx90 b/src/MNH/ch_f77.fx90
index 79387b824a2390553faa1a480964e9c3b9f034c0..be71fe6c01244c1265bc94f3e2f706cef92b5708 100644
--- a/src/MNH/ch_f77.fx90
+++ b/src/MNH/ch_f77.fx90
@@ -20,6 +20,8 @@ C**MODIFIED: 10/01/2019 (P.Wautelet) use newunit argument to open files
 C                        + bug corrections: some files were not closed
 C**MODIFIED: 10/01/2019 (P.Wautelet) replace double precision declarations by
 C                       real(kind(0.0d0)) (to allow compilation by NAG compiler)
+C**MODIFIED: 08/02/2019 (P.Wautelet) bug fixes: missing argument
+C                                             + wrong use of an non initialized value
 C!
 C!
 C!
@@ -4974,7 +4976,6 @@ c      IF(zaird .GT. nzero) aircon(izout) = zaird
 *   in subroutine.
 *   Optical depths in Lyman-alpha and SRB will be over-written
 *   in subroutine la_srb.f
-
       CALL seto2(nz,z,nw,wl,aircol,o2xs1, dto2, kout)
 
 * Ozone optical depths
@@ -20251,11 +20252,11 @@ c     INCLUDE 'params'
 
       mabs = 4
 
-      IF (mabs. EQ. 1) CALL no2xs_d(nz,tlev,nw,wl, no2xs)
-      IF (mabs .EQ. 2) CALL no2xs_jpl94(nz,tlev,nw,wl, no2xs)
-      IF (mabs .EQ. 3) CALL no2xs_har(nz,tlev,nw,wl, no2xs)
-      IF (mabs .EQ. 4) CALL no2xs_jpl06a(nz,tlev,nw,wl, no2xs)
-      IF (mabs .EQ. 5) CALL no2xs_jpl06b(nz,tlev,nw,wl, no2xs)
+      IF (mabs. EQ. 1) CALL no2xs_d(nz,tlev,nw,wl, no2xs, kout)
+      IF (mabs .EQ. 2) CALL no2xs_jpl94(nz,tlev,nw,wl, no2xs, kout)
+      IF (mabs .EQ. 3) CALL no2xs_har(nz,tlev,nw,wl, no2xs, kout)
+      IF (mabs .EQ. 4) CALL no2xs_jpl06a(nz,tlev,nw,wl, no2xs, kout)
+      IF (mabs .EQ. 5) CALL no2xs_jpl06b(nz,tlev,nw,wl, no2xs, kout)
 
 * quantum yields
 *     myld = 1   NO2_calvert.yld  (same as JPL2002)
@@ -41184,8 +41185,8 @@ c      INCLUDE 'params'
 *  Assumes that O2 = 20.95 % of air density.  If desire different O2 
 *    profile (e.g. for upper atmosphere) then can load it here.
 
-      DO iz = 1, nz
-         DO iw =1, nw - 1   
+      DO iz = 1, nz-1
+         DO iw =1, nw - 1
             dto2(iz,iw) = 0.2095 * cz(iz) * o2xs1(iw)
          ENDDO  
       ENDDO
@@ -42824,7 +42825,8 @@ c      INCLUDE 'params'
 *   calculation is based on nz-1 layers (not nz).
 
       col(nz-1) = col(nz-1) + 1.E5 * hscale * con(nz)
-  
+      col(nz) = 0.
+
 * Scale by input surface pressure:
 * min value = 1 molec cm-2