diff --git a/Fushigi/course/CourseLink.cs b/Fushigi/course/CourseLink.cs
index 85c68af4..9f293971 100644
--- a/Fushigi/course/CourseLink.cs
+++ b/Fushigi/course/CourseLink.cs
@@ -34,6 +34,11 @@ public BymlHashTable BuildNode()
 
         public ulong GetSrcHash()
         {
+            if (mSource == null)
+            {
+                return 0;
+            }
+
             return mSource.GetHash();
         }