diff --git a/src/main.zig b/src/main.zig
index e82f824..934383f 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -5,6 +5,7 @@ const max = std.math.max;
 
 const Width = 800;
 const Height = 600;
+const AspectRatio = @intToFloat(comptime_float, Width) / @intToFloat(comptime_float, Height);
 
 fn grey(value: u8) mfb.Rgb {
     return mfb.Rgb{ .r = value, .g = value, .b = value };
@@ -107,12 +108,25 @@ fn handleActive(win: mfb.Window(State), isActive: bool) callconv(.C) void {
 }
 
 fn handleResize(win: mfb.Window(State), width: i32, height: i32) callconv(.C) void {
+    const win_aspect_ratio = @intToFloat(f32, width) / @intToFloat(f32, height);
+    var vp_height: i32 = height;
+    var vp_width: i32 = width;
+    var vp_offset_x: i32 = 0;
+    var vp_offset_y: i32 = 0;
+    if (win_aspect_ratio > AspectRatio) {
+        vp_width = @floatToInt(i32, @intToFloat(f32, height) * AspectRatio);
+        vp_offset_x = @divTrunc(width - vp_width, 2);
+    } else {
+        vp_height = @floatToInt(i32, @intToFloat(f32, width) / AspectRatio);
+        vp_offset_y = @divTrunc(height - vp_height, 2);
+    }
     const did_set = win.setViewport(
-        @intCast(u32, width) / 4,
-        @intCast(u32, height) / 4,
-        @intCast(u32, width) / 2,
-        @intCast(u32, height) / 2,
-        );
+        @intCast(u32, vp_offset_x),
+        @intCast(u32, vp_offset_y),
+        @intCast(u32, vp_width),
+        @intCast(u32, vp_height),
+    );
+
     if (!did_set) {
         std.log.warn("did not set viewport!", .{});
     }