diff --git a/src/js/compiler.js b/src/js/compiler.js
index 3ddb797d..52ac51cd 100644
--- a/src/js/compiler.js
+++ b/src/js/compiler.js
@@ -32,7 +32,7 @@ function generateSpriteMatrix(dat) {
             if (ch === '.') {
                 row.push(-1);
             } else {
-                row.push(ch);
+                row.push(parseInt(ch));
             }
         }
         result.push(row);