diff --git a/src/MNH/read_exsegn.f90 b/src/MNH/read_exsegn.f90
index 83d45636d8ac4bef7534dd6e1ddab45f402761ed..d09c3323b5bc2bfe7b16b402cc8548fc51190764 100644
--- a/src/MNH/read_exsegn.f90
+++ b/src/MNH/read_exsegn.f90
@@ -1419,6 +1419,12 @@ ELSE
   END IF
 END IF
 !
+IF(CTURBLEN=='RM17') THEN
+  XCEDIS=0.34
+ELSE
+  XCEDIS=0.84
+END IF
+!
 !*       3.3  Moist turbulence
 !
 IF ( LUSERC .AND. CTURB /= 'NONE' ) THEN