diff --git a/skeleton/planet/planet.c b/skeleton/planet/planet.c
index 4bbb2f9a652ad1acc78f1942581ed2540ff7a718..684e6cc4d0236babd6910fb6f1712137923b7be0 100644
--- a/skeleton/planet/planet.c
+++ b/skeleton/planet/planet.c
@@ -55,7 +55,7 @@ vec2 vitessePerihelie(planet_t p, system_t *system)
 /// \return la position suivante d'une planète donnée
 vec2 postition_next(planet_t p, double delta_t, system_t *system)
 {
-    return vec2_add(vec2_sub(p.pos,vec2_mul(delta_t, vitessePerihelie(p,system))),vec2_mul(pow(delta_t,2)/2,acceleration(p,system)));
+    return vec2_add(vec2_add(p.pos,vec2_mul(delta_t, vitessePerihelie(p,system))),vec2_mul(pow(delta_t,2)/2,acceleration(p,system)));
 }
 
 /// Crération de planète