diff --git a/card10-l0dable/src/display.rs b/card10-l0dable/src/display.rs
index 8c0ddc27ccbb3d1ffa522fb14af2a0c752989a75..9a5a230dd62da038229dd19a727bd4a0aa8434a9 100644
--- a/card10-l0dable/src/display.rs
+++ b/card10-l0dable/src/display.rs
@@ -86,10 +86,10 @@ pub enum Font {
 
 /// Immediate mode routines
 impl Display {
-    pub const W: u16 = 160;
-    pub const H: u16 = 80;
-    pub const FONT_W: u16 = 14;
-    pub const FONT_H: u16 = 20;
+    pub const W: i16 = 160;
+    pub const H: i16 = 80;
+    pub const FONT_W: i16 = 14;
+    pub const FONT_H: i16 = 20;
 
     /// Open the display, return an instance
     pub fn open() -> Self {
diff --git a/card10-l0dable/src/framebuffer/mod.rs b/card10-l0dable/src/framebuffer/mod.rs
index 663aaafffc81ece69185c2bbd54dd45426f6721b..fef7108e3e9ceda10bcc45a3551798f969bba736 100644
--- a/card10-l0dable/src/framebuffer/mod.rs
+++ b/card10-l0dable/src/framebuffer/mod.rs
@@ -61,16 +61,16 @@ impl<'d> FrameBuffer<'d> {
 impl<'d> Index<(u16, u16)> for FrameBuffer<'d> {
     type Output = RawColor;
     fn index(&self, (x, y): (u16, u16)) -> &Self::Output {
-        let x = usize::from(Display::W - 1 - x);
-        let y = usize::from(Display::H - 1 - y);
+        let x = usize::from(Display::W as u16 - 1 - x);
+        let y = usize::from(Display::H as u16 - 1 - y);
         unsafe { transmute(&self.buffer.fb[y][x]) }
     }
 }
 
 impl<'d> IndexMut<(u16, u16)> for FrameBuffer<'d> {
     fn index_mut(&mut self, (x, y): (u16, u16)) -> &mut Self::Output {
-        let x = usize::from(Display::W - 1 - x);
-        let y = usize::from(Display::H - 1 - y);
+        let x = usize::from(Display::W as u16 - 1 - x);
+        let y = usize::from(Display::H as u16 - 1 - y);
         unsafe { transmute(&mut self.buffer.fb[y][x]) }
     }
 }
@@ -85,7 +85,7 @@ impl<'d, C: PixelColor + Into<RawColor>> Drawing<C> for FrameBuffer<'d> {
             let x = coord[0] as u16;
             let y = coord[1] as u16;
 
-            if x >= Display::W || y >= Display::H {
+            if x >= Display::W as u16 || y >= Display::H as u16 {
                 continue;
             }
             // Swap bytes
diff --git a/card10-l0dable/src/framebuffer/text.rs b/card10-l0dable/src/framebuffer/text.rs
index cb30d1f451a886a970b29b7cd29e966f6e0faaa1..1627b488afdbe7b01df96aa8d63a10f280ada873 100644
--- a/card10-l0dable/src/framebuffer/text.rs
+++ b/card10-l0dable/src/framebuffer/text.rs
@@ -24,10 +24,10 @@ impl<'a, 'd, 'f> Write for TextRenderer<'a, 'd, 'f> {
             Some(glyph) => {
                 for y in 0..self.font.h {
                     let y1 = (self.y + y as isize) as u16;
-                    if y1 < Display::H {
+                    if y1 < Display::H as u16 {
                         for x in 0..self.font.w {
                             let x1 = (self.x + x as isize) as u16;
-                            if x1 < Display::W {
+                            if x1 < Display::W as u16 {
                                 if glyph.get_pixel(x as usize, y as usize) {
                                     self.framebuffer[(x1, y1)] = self.color;
                                 }
diff --git a/rkanoid/src/main.rs b/rkanoid/src/main.rs
index 0c5e91a0e8dd10e74551288ee749f8dab05bc23a..cba4902b234a40ed67d2bb8e787e3f8179bddf9a 100644
--- a/rkanoid/src/main.rs
+++ b/rkanoid/src/main.rs
@@ -184,7 +184,7 @@ fn game(level: u16, mut score: u32) -> GameResult {
     let mut blocks = Blocks::generate((0x3F + 0x10 * level).min(0xff) as u8);
 
     // Clear screen
-    draw_rect(&mut fb, 0, 0, Display::W - 1, Display::H - 1, RawColor::black());
+    draw_rect(&mut fb, 0, 0, Display::W as u16 - 1, Display::H as u16 - 1, RawColor::black());
     // Draw Blocks
     for (lineno, line) in blocks.blocks.iter_mut().enumerate() {
         let lineno = lineno as u32;
@@ -299,11 +299,11 @@ fn game(level: u16, mut score: u32) -> GameResult {
         }
         // Space below blocks
         draw_rect(&mut fb, 0, (BLOCK_H * BLOCKS_Y) as u16,
-                  Display::W, Display::H, RawColor::black());
+                  Display::W as u16, Display::H as u16, RawColor::black());
         // Paddle
         draw_rect(&mut fb,
-                  (paddle - paddle_size) as u16, Display::H - PADDLE_HEIGHT as u16,
-                  (paddle + paddle_size) as u16, Display::H - 1,
+                  (paddle - paddle_size) as u16, Display::H as u16 - PADDLE_HEIGHT as u16,
+                  (paddle + paddle_size) as u16, Display::H as u16 - 1,
                   RawColor::rgb8(0x7f, 0xff, 0x7f));
         // Ball
         fb.draw(
@@ -412,10 +412,10 @@ fn main() {
 }
 
 fn draw_rect(fb: &mut FrameBuffer, x1: u16, y1: u16, x2: u16, y2: u16, color: RawColor) {
-    let x1 = x1.max(0).min(Display::W - 1);
-    let x2 = x2.max(0).min(Display::W - 1);
-    let y1 = y1.max(0).min(Display::H - 1);
-    let y2 = y2.max(0).min(Display::H - 1);
+    let x1 = x1.max(0).min(Display::W as u16 - 1);
+    let x2 = x2.max(0).min(Display::W as u16 - 1);
+    let y1 = y1.max(0).min(Display::H as u16 - 1);
+    let y2 = y2.max(0).min(Display::H as u16 - 1);
     for y in y1..=y2 {
         for x in x1..=x2 {
             fb[(x, y)] = color;