diff --git a/src/lsystem/engine/Parser.java b/src/lsystem/engine/Parser.java
index 366bd3d..5ca6096 100644
--- a/src/lsystem/engine/Parser.java
+++ b/src/lsystem/engine/Parser.java
@@ -156,7 +156,7 @@ public class Parser {
                 }
             }
         }
-        assert root == null;
+        assert root != null;
         return root;
     }