diff --git a/src/hydro/Gadget2/hydro.h b/src/hydro/Gadget2/hydro.h
index 60f07c2fc31fd5f38d2929679d0e13beb1cc9131..d2d4450fa12374a8a8dec624c5e54ba3d47b99aa 100644
--- a/src/hydro/Gadget2/hydro.h
+++ b/src/hydro/Gadget2/hydro.h
@@ -320,7 +320,8 @@ __attribute__((always_inline)) INLINE static void hydro_end_force(
 
   p->force.h_dt *= p->h * hydro_dimension_inv;
 
-  p->entropy_dt *= hydro_gamma_minus_one * pow_minus_gamma_minus_one(p->rho);
+  p->entropy_dt *=
+      0.5f * hydro_gamma_minus_one * pow_minus_gamma_minus_one(p->rho);
 }
 
 /**
diff --git a/src/hydro/Gadget2/hydro_iact.h b/src/hydro/Gadget2/hydro_iact.h
index d37ac491fe5d8ecdf127c217ca025080daf4bbfd..b87201530758f9b50d3873ac2ac4dd84b7602d47 100644
--- a/src/hydro/Gadget2/hydro_iact.h
+++ b/src/hydro/Gadget2/hydro_iact.h
@@ -469,8 +469,8 @@ __attribute__((always_inline)) INLINE static void runner_iact_force(
   pj->force.v_sig = fmaxf(pj->force.v_sig, v_sig);
 
   /* Change in entropy */
-  pi->entropy_dt += 0.5f * mj * visc_term * dvdr;
-  pj->entropy_dt += 0.5f * mi * visc_term * dvdr;
+  pi->entropy_dt += mj * visc_term * dvdr;
+  pj->entropy_dt += mi * visc_term * dvdr;
 }
 
 /**
@@ -631,7 +631,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_vec_force(
   pjh_dt.v = mi.v * dvdr.v * ri.v / pirho.v * wj_dr.v;
 
   /* Change in entropy */
-  entropy_dt.v = vec_set1(0.5f) * visc_term.v * dvdr.v;
+  entropy_dt.v = visc_term.v * dvdr.v;
 
   /* Store the forces back on the particles. */
   for (k = 0; k < VEC_SIZE; k++) {
@@ -738,7 +738,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_force(
   pi->force.v_sig = fmaxf(pi->force.v_sig, v_sig);
 
   /* Change in entropy */
-  pi->entropy_dt += 0.5f * mj * visc_term * dvdr;
+  pi->entropy_dt += mj * visc_term * dvdr;
 }
 
 /**
@@ -894,7 +894,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_vec_force(
   pih_dt.v = mj.v * dvdr.v * ri.v / pjrho.v * wi_dr.v;
 
   /* Change in entropy */
-  entropy_dt.v = vec_set1(0.5f) * mj.v * visc_term.v * dvdr.v;
+  entropy_dt.v = mj.v * visc_term.v * dvdr.v;
 
   /* Store the forces back on the particles. */
   for (k = 0; k < VEC_SIZE; k++) {