diff --git a/src/cosmology.c b/src/cosmology.c
index a5034240d07b9b9bf401d470c0bacbf6962a8006..4da9528784b1fb7fdb04761b77a3c0056a32f41a 100644
--- a/src/cosmology.c
+++ b/src/cosmology.c
@@ -642,8 +642,12 @@ void cosmology_write_model(hid_t h_grp, const struct cosmology *c) {
   io_write_attribute_d(h_grp, "a_end", c->a_end);
   io_write_attribute_d(h_grp, "time_beg [internal units]", c->time_begin);
   io_write_attribute_d(h_grp, "time_end [internal units]", c->time_end);
+  io_write_attribute_d(h_grp, "Universe age [internal units]", c->time);
+  io_write_attribute_d(h_grp, "Lookback time [internal units]",
+                       c->lookback_time);
   io_write_attribute_d(h_grp, "h", c->h);
   io_write_attribute_d(h_grp, "H0 [internal units]", c->H0);
+  io_write_attribute_d(h_grp, "H [internal units]", c->H);
   io_write_attribute_d(h_grp, "Hubble time [internal units]", c->Hubble_time);
   io_write_attribute_d(h_grp, "Omega_m", c->Omega_m);
   io_write_attribute_d(h_grp, "Omega_r", c->Omega_r);
@@ -652,6 +656,11 @@ void cosmology_write_model(hid_t h_grp, const struct cosmology *c) {
   io_write_attribute_d(h_grp, "Omega_lambda", c->Omega_lambda);
   io_write_attribute_d(h_grp, "w_0", c->w_0);
   io_write_attribute_d(h_grp, "w_a", c->w_a);
+  io_write_attribute_d(h_grp, "w", c->w);
+  io_write_attribute_d(h_grp, "Redshift", c->z);
+  io_write_attribute_d(h_grp, "Scale-factor", c->a);
+  io_write_attribute_d(h_grp, "Critical density [internal units]",
+                       c->critical_density);
 }
 #endif
 
diff --git a/src/parallel_io.c b/src/parallel_io.c
index 51c88e95396eb6af1ab7f7eb2d1ed48eada59e0d..1446a3010268f2d02042a6b6496d8dee4035a4c4 100644
--- a/src/parallel_io.c
+++ b/src/parallel_io.c
@@ -904,6 +904,7 @@ void prepare_file(struct engine* e, const char* baseName, long long N_total[6],
   io_write_attribute(h_grp, "Dimension", INT, &dimension, 1);
   io_write_attribute(h_grp, "Redshift", DOUBLE, &e->cosmology->z, 1);
   io_write_attribute(h_grp, "Scale-factor", DOUBLE, &e->cosmology->a, 1);
+  io_write_attribute_s(h_grp, "Code", "SWIFT");
 
   /* GADGET-2 legacy values */
   /* Number of particles of each type */
diff --git a/src/serial_io.c b/src/serial_io.c
index dd623f946ce6ec32415586e5048979de3adb58fa..a088e71fbe0c15f5aa8503d55fae664d25fcbab1 100644
--- a/src/serial_io.c
+++ b/src/serial_io.c
@@ -812,6 +812,7 @@ void write_output_serial(struct engine* e, const char* baseName,
     io_write_attribute(h_grp, "Dimension", INT, &dimension, 1);
     io_write_attribute(h_grp, "Redshift", DOUBLE, &e->cosmology->z, 1);
     io_write_attribute(h_grp, "Scale-factor", DOUBLE, &e->cosmology->a, 1);
+    io_write_attribute_s(h_grp, "Code", "SWIFT");
 
     /* GADGET-2 legacy values */
     /* Number of particles of each type */
diff --git a/src/single_io.c b/src/single_io.c
index 2170bcffc4ce3ab21f1edd168d1dc37b2b4af963..452c4fe27a983fd6c05733916131b962ef1f7939 100644
--- a/src/single_io.c
+++ b/src/single_io.c
@@ -666,6 +666,7 @@ void write_output_single(struct engine* e, const char* baseName,
   io_write_attribute(h_grp, "Dimension", INT, &dimension, 1);
   io_write_attribute(h_grp, "Redshift", DOUBLE, &e->cosmology->z, 1);
   io_write_attribute(h_grp, "Scale-factor", DOUBLE, &e->cosmology->a, 1);
+  io_write_attribute_s(h_grp, "Code", "SWIFT");
 
   /* GADGET-2 legacy values */
   /* Number of particles of each type */