diff --git a/src/netcdf/netcdf.f90 b/src/netcdf/netcdf.f90
index 0a9e7cfd8..c36408a72 100644
--- a/src/netcdf/netcdf.f90
+++ b/src/netcdf/netcdf.f90
@@ -353,9 +353,9 @@ module subroutine netcdf_open(self, param, readonly)
       character(len=NF90_MAX_NAME) :: str_dim_name
 
       mode = NF90_WRITE
-      !if (present(readonly)) then
-      !   if (readonly) mode = NF90_NOWRITE
-      !end if
+      if (present(readonly)) then
+         if (readonly) mode = NF90_NOWRITE
+      end if
 
       call check( nf90_open(param%outfile, mode, self%ncid), "netcdf_open nf90_open" )