diff --git a/cv9/snake.c b/cv9/snake.c
index 851e992..66a6b5e 100644
--- a/cv9/snake.c
+++ b/cv9/snake.c
@@ -40,11 +40,13 @@ void free_snake(struct snake* sn){
 }
 
 int is_snake(struct snake* snake,int x,int y){
-    if(snake == NULL)
-        return NULL;
-    if(snake->x == x && snake->y == y)
-        return 1;
-    return 0;
+    struct snake* this = snake;
+    while(this != NULL){
+        if(this->x == x && this->y == y)
+            return 1;
+    this = this->next;
+    }
+        return 0;
 }
 
 int step_state(struct state* st){