diff --git a/src/prec.f90 b/src/prec.f90
index 959ee77ba..f6c0fd543 100644
--- a/src/prec.f90
+++ b/src/prec.f90
@@ -7,6 +7,7 @@
 !> @brief    setting precision for real and int type
 !--------------------------------------------------------------------------------------------------
 module prec
+! ToDo:    use, intrinsic :: iso_fortran_env, only : I8 => int64, WP => real64 
  implicit none
  private 
 #if (FLOAT==8)