diff --git a/src/hydro/Default/hydro_part.h b/src/hydro/Default/hydro_part.h
index 6bfe81822f1519b1239428234a72a48868cf170e..2cb5345578f51ea6879f48d5e2adeba33a3d808e 100644
--- a/src/hydro/Default/hydro_part.h
+++ b/src/hydro/Default/hydro_part.h
@@ -29,9 +29,6 @@ struct xpart {
   /* Velocity at the last full step. */
   float v_full[3];
 
-  /* Entropy at the half-step. */
-  float u_hdt;
-
   /* Old density. */
   float omega;
 
diff --git a/src/hydro/Gadget2/hydro_part.h b/src/hydro/Gadget2/hydro_part.h
index 45c04ba75cefc51465ccb8cff4cee029c4f237e3..fea9ee54aaefbff0e7e5c8dfdb96950cbe5592ac 100644
--- a/src/hydro/Gadget2/hydro_part.h
+++ b/src/hydro/Gadget2/hydro_part.h
@@ -29,12 +29,6 @@ struct xpart {
   /* Velocity at the last full step. */
   float v_full[3];
 
-  /* Entropy at the half-step. */
-  float u_hdt;
-
-  /* Old density. */
-  float omega;
-
 } __attribute__((aligned(xpart_align)));
 
 /* Data of a single particle. */
diff --git a/src/runner.c b/src/runner.c
index 88a94f0dcd9fb1b92b5109058d81c28f781bd1a0..ade14ee625136c9ed2b6bc22ac1e0f539e320bf9 100644
--- a/src/runner.c
+++ b/src/runner.c
@@ -944,7 +944,7 @@ void runner_dokick(struct runner *r, struct cell *c, int timer) {
       /* Collect total energy. */
       ekin += 0.5 * m * (v_full[0] * v_full[0] + v_full[1] * v_full[1] +
                          v_full[2] * v_full[2]);
-      epot += m * xp->u_hdt;
+      epot += 0.f; //MATTHIEU
 
       /* Minimal time for next end of time-step */
       t_end_min = fminf(p->t_end, t_end_min);