diff --git a/src/mo_fortran_tools.F90 b/src/mo_fortran_tools.F90
index 8df4ada4ae3ab8008d39a91f3afb7257a59655fc..9646cd82a60228aa5522bd76483cf9192ea094a2 100644
--- a/src/mo_fortran_tools.F90
+++ b/src/mo_fortran_tools.F90
@@ -1813,7 +1813,7 @@ CONTAINS
 
     minval_2d = HUGE(minval_2d)
 
-    !$ACC PARALLEL LOOP GANG VECTOR DEFAULT(PRESENT) ASYNC(1) REDUCTION(MIN: minval_2d) IF(lzacc) COPY(minval_2d)
+    !$ACC PARALLEL LOOP GANG VECTOR DEFAULT(PRESENT) ASYNC(1) COLLAPSE(2) REDUCTION(MIN: minval_2d) IF(lzacc) COPY(minval_2d)
     DO j = 1, s2
       DO i = 1, s1
         minval_2d = MIN(minval_2d, var(i, j)) ! The loop is equivalent to MINVAL(var(:,:))