diff --git a/main.c b/main.c
index 26bc415c52df537c6dfd3cc24644abd7fbc51339..c9092e0cef7913b255053c7ba4bc200433717852 100644
--- a/main.c
+++ b/main.c
@@ -221,7 +221,16 @@ 	glClearColor(0.4, 0.4, 1.0, 0.0);
 	glEnable(GL_DEPTH_TEST);
 	glMatrixMode(GL_PROJECTION);
 	glLoadIdentity();
-	glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
+
+	int w = game.width;
+	int h = game.height;
+	if (h == 0) h = 1;
+	float aspect = (float)w / (float)h;
+	if (w >= h) {
+		glOrtho(0.5 - 0.5 * aspect, 0.5 + 0.5 * aspect, 0.0, 1.0, -1.0, 1.0);
+	} else {
+		glOrtho(0.0, 1.0, 0.5 - 0.5 / aspect, 0.5 + 0.5 / aspect, -1.0, 1.0);
+	}
 }
 
 void handle_mouse_event(int button, int state, int x, int y) {
@@ -264,10 +273,18 @@ 	}
 }
 
 void handle_reshape(int w, int h) {
+	if (h == 0) h = 1;
 	glViewport (0, 0, (GLsizei) w, (GLsizei) h);
 	glMatrixMode(GL_PROJECTION);
 	glLoadIdentity();
-	glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
+
+	float aspect = (float)w / (float)h;
+	if (w >= h) {
+		glOrtho(0.5 - 0.5 * aspect, 0.5 + 0.5 * aspect, 0.0, 1.0, -1.0, 1.0);
+	} else {
+		glOrtho(0.0, 1.0, 0.5 - 0.5 / aspect, 0.5 + 0.5 / aspect, -1.0, 1.0);
+	}
+
 	glMatrixMode(GL_MODELVIEW);
 	glLoadIdentity();
 }