diff --git a/src/MNH/lima_ccn_activation.f90 b/src/MNH/lima_ccn_activation.f90
index 884c98379005ec3379a966730f7c275d3ac1fbc2..fd2a2282a64e0d82bf6f6cd8db7b09e514c09566 100644
--- a/src/MNH/lima_ccn_activation.f90
+++ b/src/MNH/lima_ccn_activation.f90
@@ -472,7 +472,7 @@ IF ( OCLOSE_OUT ) THEN
   TZFIELD%CMNHNAME   ='NACT'
   TZFIELD%CSTDNAME   = ''
   TZFIELD%CLONGNAME  = TRIM(TZFIELD%CMNHNAME)
-  TZFIELD%CUNITS     = '/kg'
+  TZFIELD%CUNITS     = 'kg-1'
   TZFIELD%CDIR       = 'XY'
   TZFIELD%CCOMMENT   = 'X_Y_Z_NACT'
   TZFIELD%NGRID      = 1
diff --git a/src/MNH/lima_warm_nucl.f90 b/src/MNH/lima_warm_nucl.f90
index 66b235e485fe9105fbbff74cb47cca091c47080b..046ceeaeadb321805e62cc3c3353ae138d65cb62 100644
--- a/src/MNH/lima_warm_nucl.f90
+++ b/src/MNH/lima_warm_nucl.f90
@@ -540,7 +540,7 @@ IF ( OCLOSE_OUT ) THEN
   TZFIELD%CMNHNAME   ='NACT'
   TZFIELD%CSTDNAME   = ''
   TZFIELD%CLONGNAME  = TRIM(TZFIELD%CMNHNAME)
-  TZFIELD%CUNITS     = '/kg'
+  TZFIELD%CUNITS     = 'kg-1'
   TZFIELD%CDIR       = 'XY'
   TZFIELD%CCOMMENT   = 'X_Y_Z_NACT'
   TZFIELD%NGRID      = 1