1 files changed, 2 insertions, 1 deletions
diff --git a/lsys.js b/lsys.js
index 8f7ec49..b102107 100644
--- a/lsys.js
+++ b/lsys.js
@@ -13,8 +13,9 @@ function LSystem(axiom, rules) {
   };
 
   this.draw = function(alpha) {
-    if (alpha === undefined)
+    if (!alpha) {
       alpha = 90 * (Math.PI / 180);
+    }
 
     var coords = [];
     var stack = [];