diff --git a/src/box.c b/src/box.c
index e014332..7c5c5c4 100644
--- a/src/box.c
+++ b/src/box.c
@@ -29,6 +29,8 @@
 box * create_box(game *g, int x, int y, int w, int h)
 {
     box *b = malloc(sizeof(box));
+    if(b == NULL)
+        exit(1);
 
     b->x = x;
     b->y = y;
diff --git a/src/main.c b/src/main.c
index 11afcb5..cbe6a7f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -36,6 +36,8 @@ static void start_game (game *);
 int main (int argc, char **argv)
 {
     game *g = malloc(sizeof(game));
+    if(g == NULL)
+        exit(1);
 
     srand(time(NULL));
 
@@ -70,11 +72,19 @@ static void start_game (game *g)
 
     g->sf = create_starfield(g);
     g->wp = malloc(sizeof(weapons));
+    if(g->wp == NULL)
+        exit(1);
     g->ex = malloc(sizeof(explosions));
+    if(g->ex == NULL)
+        exit(1);
     g->bo = malloc(sizeof(bonus));
+    if(g->bo == NULL)
+        exit(1);
     g->t = create_tunnel(g, g->w, g->h);
     g->p = create_player(g);
     g->al = malloc(sizeof(aliens));
+    if(g->al == NULL)
+        exit(1);
 
     init_bonus(g, g->bo);
     init_weapons(g, g->wp);
diff --git a/src/player.c b/src/player.c
index 0daac48..2644438 100644
--- a/src/player.c
+++ b/src/player.c
@@ -32,6 +32,8 @@ struct ee_sprite *ship_sprite;
 player * create_player(game *g)
 {
     player *p = malloc(sizeof(player));
+    if(p == NULL)
+        exit(1);
 
     p->x = g->w / 2;
     p->y = g->h - 3;
diff --git a/src/starfield.c b/src/starfield.c
index 60f408b..de4a24b 100644
--- a/src/starfield.c
+++ b/src/starfield.c
@@ -32,6 +32,8 @@ starfield * create_starfield(game *g)
     starfield *s;
 
     s = malloc(STARS * sizeof(starfield));
+    if(s == NULL)
+        exit(1);
 
     for(i = 0; i < STARS; i++)
     {
diff --git a/src/tunnel.c b/src/tunnel.c
index b6f4c31..fb80333 100644
--- a/src/tunnel.c
+++ b/src/tunnel.c
@@ -31,9 +31,15 @@ tunnel * create_tunnel(game *g, int w, int h)
 {
     int i;
     tunnel *t = malloc(sizeof(tunnel));
+    if(t == NULL)
+        exit(1);
 
     t->left = malloc(h*sizeof(int));
+    if(t->left == NULL)
+        exit(1);
     t->right = malloc(h*sizeof(int));
+    if(t->right == NULL)
+        exit(1);
     t->w = w;
     t->h = h;
 
diff --git a/src/weapons.c b/src/weapons.c
index 6420246..15eff17 100644
--- a/src/weapons.c
+++ b/src/weapons.c
@@ -169,7 +169,7 @@ void update_weapons(game *g, weapons *wp)
                 /* Normalize direction */
                 if(dx | dy)
                 {
-                    int norm = ee_sqrt(dx * dx + 4 * dy * dy);
+                    unsigned int norm = ee_sqrt(dx * dx + 4 * dy * dy);
                     dx = dx * 32 / norm;
                     dy = dy * 32 / norm;
                 }
@@ -181,7 +181,7 @@ void update_weapons(game *g, weapons *wp)
                 /* Normalize speed */
                 if(dx | dy)
                 {
-                    int norm = ee_sqrt(dx * dx + 4 * dy * dy);
+                    unsigned int norm = ee_sqrt(dx * dx + 4 * dy * dy);
                     wp->vx[i] = dx * 32 / norm;
                     wp->vy[i] = dy * 32 / norm;
                 }