diff --git a/src/exception.cpp b/src/exception.cpp
new file mode 100644
index 0000000..22f89a1
--- /dev/null
+++ b/src/exception.cpp
@@ -0,0 +1,17 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2013, Regents of the University of California
+ *                     Yingdi Yu
+ *
+ * BSD license, See the LICENSE file for more information
+ *
+ * Author: Yingdi Yu <yingdi@cs.ucla.edu>
+ */
+
+#include "exception.h"
+
+using namespace std;
+
+LnException::LnException(const string & errMsg) throw()
+  : m_errMsg(errMsg)
+{}