diff --git a/src/MNH/tridiag_tke.f90 b/src/MNH/tridiag_tke.f90
index ee15d6a7ba9d0033ac47c6a26d61e6696c0ea467..b4743a2123ed7607ebce235b476e6b9b1284155b 100644
--- a/src/MNH/tridiag_tke.f90
+++ b/src/MNH/tridiag_tke.f90
@@ -256,8 +256,9 @@ IF ( PIMPL > 1.E-10 ) THEN
      PVARP(JI,JJ,IKB) = ZY(JI,JJ,IKB) / ZBET(JI,JJ)
   END DO !CONCURRENT
   !
+  !$acc loop  seq
   DO JK = IKB+KKL,IKE-KKL,KKL
-!$acc loop collapse(2) independent
+   !$acc loop gang, vector collapse(2) independent
     DO JJ=1,JJU
       DO JI=1,JIU
         ZGAM(JI,JJ,JK) = PIMPL * PA(JI,JJ,JK) / PRHODJ(JI,JJ,JK-KKL) / ZBET(JI,JJ)