diff --git a/src/MNH/subl_blowsnow.f90 b/src/MNH/subl_blowsnow.f90
index ad0cf278fa86b1eeedaf7c0a2da1344d8d86024a..96c6b9be4432ef3ee07b4f7d79368c232ca113d7 100644
--- a/src/MNH/subl_blowsnow.f90
+++ b/src/MNH/subl_blowsnow.f90
@@ -696,6 +696,7 @@ ZFCRI = MAX(ZFCRI1,ZFCRI2)
 !*      2    Calculate variances of the horizontal and vertical velocity components
 !
 ZS0   = ZFCRI*PZZ/PVMOD
+STOP 'Bug in TURB_FLUC: ZUSTAR used but not set'
 ZSIGU = 4.77 *ZUSTAR**2/ (1+33*ZS0)**0.66666
 ZSIGV = 2.76 *ZUSTAR**2/ (1+9.5*ZS0)**0.66666
 ZSIGW = 1.31 *ZUSTAR**2/ (1+3.12*ZS0)**0.66666