diff --git a/Implab/Parsing/DFADefinition.cs b/Implab/Parsing/DFADefinition.cs
--- a/Implab/Parsing/DFADefinition.cs
+++ b/Implab/Parsing/DFADefinition.cs
@@ -256,7 +256,9 @@ namespace Implab.Parsing {
         }
 
         public int AlphabetSize {
-            get;
+            get {
+                return m_alpabetSize;
+            }
         }
     }
 }