diff --git a/src/hydro/PressureEnergy/hydro_io.h b/src/hydro/PressureEnergy/hydro_io.h
index c9ad03e558cd117731cf1e597a2603d92f801ad5..a213ce870e1085e06c5d852e71e266432589a971 100644
--- a/src/hydro/PressureEnergy/hydro_io.h
+++ b/src/hydro/PressureEnergy/hydro_io.h
@@ -76,7 +76,7 @@ void convert_u(const struct engine* e, const struct part* p,
 void convert_S(const struct engine* e, const struct part* p,
 	       const struct xpart* xp, float*ret) {
   
-  ret[0] = hydro_get_entropy(p);
+  ret[0] = hydro_get_comoving_entropy(p);
 }
 
 void convert_P(const struct engine* e, const struct part* p,