diff --git a/pmc/main.cc b/pmc/main.cc
--- a/pmc/main.cc
+++ b/pmc/main.cc
@@ -16,6 +16,8 @@
 
 #define MAX 3
 
+using namespace algebra;
+
 int main (int argc, char **argv)
 {
     Surface *surface;
@@ -45,7 +47,7 @@
     d[2] = new Cube (surface, p1, p2, p3, p4, height);
 
     bool running = true;
-    int x, y;
+    int i, x, y;
 
     x = y = 0;
 
@@ -60,7 +62,7 @@
 
         if (event.type == SDL_KEYDOWN) {
             surface->setColor (Surface::BLACK);
-            for (int i = 0; i < MAX; i++)
+            for (i = 0; i < MAX; i++)
                 d[i]->show ();
             surface->setColor (Surface::RED);
 
@@ -70,29 +72,29 @@
                 break;
 
             case SDLK_UP:
-                for (int i = 0; i < MAX; i++)
+                for (i = 0; i < MAX; i++)
                     d[i]->move ((Vector (x, y - STEP)));
                 break;
 
             case SDLK_DOWN:
-                for (int i = 0; i < MAX; i++)
+                for (i = 0; i < MAX; i++)
                     d[i]->move ((Vector (x, y + STEP)));
                 break;
 
             case SDLK_LEFT:
-                for (int i = 0; i < MAX; i++)
+                for (i = 0; i < MAX; i++)
                     d[i]->move ((Vector (x - STEP, y)));
                 break;
 
             case SDLK_RIGHT:
-                for (int i = 0; i < MAX; i++)
+                for (i = 0; i < MAX; i++)
                     d[i]->move ((Vector (x + STEP, y)));
                 break;
             default:
                 break;
             }
 
-            for (int i = 0; i < MAX; i++) {
+            for (i = 0; i < MAX; i++) {
                 d[i]->show ();
             }
 
@@ -100,7 +102,7 @@
         }
     }
 
-    for (int i = 0; i < MAX; i++)
+    for (i = 0; i < MAX; i++)
         delete d[i];
 
     delete surface;