diff --git a/src/util/util_index_array.f90 b/src/util/util_index_array.f90
index d6b214267..a72ac1b17 100644
--- a/src/util/util_index_array.f90
+++ b/src/util/util_index_array.f90
@@ -22,8 +22,8 @@ module subroutine util_index_array(ind_arr, n)
          nold = 0
       end if
 
+      allocate(itmp(n))
       if (n >= nold) then
-         allocate(itmp(n))
          if (nold > 0) itmp(1:nold) = ind_arr(1:nold)
          itmp(nold+1:n) = [(i, i = nold + 1, n)]
          call move_alloc(itmp, ind_arr)