diff --git a/src/gravity/Default/gravity.h b/src/gravity/Default/gravity.h
index f8365e54dbb78eba0df1ea24452dc95079d396ca..7349ad8e224ccfee8504d65cef2d0f5ac47d9998 100644
--- a/src/gravity/Default/gravity.h
+++ b/src/gravity/Default/gravity.h
@@ -76,7 +76,9 @@ gravity_compute_timestep_self(const struct phys_const* const phys_const,
  * @param gp The particle to act upon
  */
 __attribute__((always_inline)) INLINE static void gravity_first_init_gpart(
-    struct gpart* gp) {}
+    struct gpart* gp) {
+  gp->epsilon = 0.1;  // MATTHIEU
+}
 
 /**
  * @brief Prepares a g-particle for the gravity calculation
diff --git a/src/gravity/Default/gravity_iact.h b/src/gravity/Default/gravity_iact.h
index a579127dc38c584cbad009dad9f0c2f2e1fcdde2..d0624ab2b23f6098aa21f32dda81bc83e6f2489c 100644
--- a/src/gravity/Default/gravity_iact.h
+++ b/src/gravity/Default/gravity_iact.h
@@ -47,31 +47,30 @@ __attribute__((always_inline)) INLINE static void runner_iact_grav_pp(
   const float uj = r * hj_inv;
   float fi, fj, W;
 
-  if(r >= hi) {
-    
+  if (r >= hi) {
+
     /* Get Newtonian graavity */
     fi = mj * ir * ir * ir;
-    
+
   } else {
-    
+
     /* Get softened gravity */
     kernel_grav_eval(ui, &W);
     fi = mj * hi_inv3 * W;
   }
 
-  if(r >= hj) {
-    
+  if (r >= hj) {
+
     /* Get Newtonian graavity */
     fj = mi * ir * ir * ir;
-    
+
   } else {
-    
+
     /* Get softened gravity */
     kernel_grav_eval(uj, &W);
     fj = mi * hj_inv3 * W;
   }
 
-  
   const float fidx[3] = {fi * dx[0], fi * dx[1], fi * dx[2]};
   gpi->a_grav[0] -= fidx[0];
   gpi->a_grav[1] -= fidx[1];