diff --git a/assimilation_code/modules/observations/obs_sequence_mod.f90 b/assimilation_code/modules/observations/obs_sequence_mod.f90
index 2499ca5644..1940e46c28 100644
--- a/assimilation_code/modules/observations/obs_sequence_mod.f90
+++ b/assimilation_code/modules/observations/obs_sequence_mod.f90
@@ -2505,7 +2505,7 @@ subroutine write_obs(obs, file_id, num_copies, num_qc)
    write(file_id) obs%prev_time, obs%next_time, obs%cov_group
    call write_obs_def(file_id, obs%def, obs%key, 'unformatted')
 else
-   write(file_id, *) obs%prev_time, obs%next_time, obs%cov_group
+   write(file_id, "(A,I8,A,I8,A,I8)") "    ", obs%prev_time, "     ", obs%next_time, "   ", obs%cov_group
    call write_obs_def(file_id, obs%def, obs%key)
 endif