diff --git a/gtsam/base/FastSet.h b/gtsam/base/FastSet.h
index 810a48c60..29fb3fcd9 100644
--- a/gtsam/base/FastSet.h
+++ b/gtsam/base/FastSet.h
@@ -19,9 +19,8 @@
 #pragma once
 
 #include <gtsam/base/FastDefaultAllocator.h>
-
 #include <set>
-#include <iosfwd>
+#include <iostream>
 #include <string>
 #include <cmath>
 #include <boost/mpl/has_xxx.hpp>
diff --git a/gtsam/base/Vector.h b/gtsam/base/Vector.h
index d19fee298..1c433eb4a 100644
--- a/gtsam/base/Vector.h
+++ b/gtsam/base/Vector.h
@@ -23,6 +23,7 @@
 #include <list>
 #include <gtsam/global_includes.h>
 #include <gtsam/3rdparty/Eigen/Eigen/Core>
+#include <iostream>
 namespace gtsam {
 
 // Vector is just a typedef of the Eigen dynamic vector type
diff --git a/gtsam/base/types.h b/gtsam/base/types.h
index d0ba526c2..122bc18a0 100644
--- a/gtsam/base/types.h
+++ b/gtsam/base/types.h
@@ -21,7 +21,6 @@
 
 #include <gtsam/dllexport.h>
 #include <gtsam/config.h>
-#include <iostream>
 #include <cstddef>
 #include <string>
 #include <ostream>
@@ -33,6 +32,7 @@
 #include <tbb/task_scheduler_init.h>
 #include <tbb/tbb_exception.h>
 #include <tbb/scalable_allocator.h>
+#include <iostream>
 #endif
 
 #ifdef GTSAM_USE_EIGEN_MKL_OPENMP