diff --git a/Makefile b/Makefile
index 7de7005..da1c3a0 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,8 @@ GTK_PACKAGES=gdk-pixbuf-2.0 gtk+-2.0
 GTK_CFLAGS=$(shell pkg-config --cflags $(GTK_PACKAGES))
 GTK_LIBS=$(shell pkg-config --libs $(GTK_PACKAGES))
 
-CFLAGS=-Wall -g -O2 $(GTK_CFLAGS)
+# PROFILING_CFLAGS=-pg
+CFLAGS=-Wall -g -O2 $(PROFILING_CFLAGS) $(GTK_CFLAGS)
 
 LIBS=$(GTK_LIBS)
 
diff --git a/balls.c b/balls.c
index 651cfcb..48bf475 100644
--- a/balls.c
+++ b/balls.c
@@ -97,7 +97,7 @@ static void ball_collision (struct ball * p, struct ball * q) {
     }
 }
 
-static void ball_update_state (struct ball * p) {
+void ball_update_state (struct ball * p) {
     p->x += delta*p->v_x + delta*delta*g_x/2.0;
     p->v_x += delta*g_x;
 
@@ -129,16 +129,23 @@ static void ball_update_state (struct ball * p) {
     } 
 }
 
-static void update_state () {
-    if (collisions) {
-	for(int i = 0; i < n_balls; ++i)
-	    for(int j = i + 1; j < n_balls; ++j)
-		ball_collision(balls + i, balls + j);
-    }
+void movement_and_borders () {
     for(int i = 0; i < n_balls; ++i)
 	ball_update_state(balls + i);
 }
 
+void check_collisions () {
+    for(int i = 0; i < n_balls; ++i)
+	for(int j = i + 1; j < n_balls; ++j)
+	    ball_collision(balls + i, balls + j);
+}
+
+static void update_state () {
+    if (collisions)
+	check_collisions();
+    movement_and_borders();
+}
+
 /* Graphics System
  */