diff --git a/src/gradient-flow.cc b/src/gradient-flow.cc
index 187b9c346afed0100496103cbe00f8c9c98db623..875b800cab2d1a6e78608b79116467ac5a8739e1 100644
--- a/src/gradient-flow.cc
+++ b/src/gradient-flow.cc
@@ -309,6 +309,6 @@ int main (int argc, char *argv[]) try
 }
 catch (Exception e)
 {
-  std::cout << e << std::endl;
+  std::cout << e.what() << std::endl;
   return 1;
 }