diff --git a/gtsam/base/Matrix.cpp b/gtsam/base/Matrix.cpp
index f71f6fce8f..5b8a021d44 100644
--- a/gtsam/base/Matrix.cpp
+++ b/gtsam/base/Matrix.cpp
@@ -34,7 +34,6 @@
 #include <fstream>
 #include <limits>
 #include <iostream>
-#include <iostream>
 
 using namespace std;