diff --git a/gtsam/nonlinear/Expression-inl.h b/gtsam/nonlinear/Expression-inl.h
index 3ab0bfe4d..f9f81c598 100644
--- a/gtsam/nonlinear/Expression-inl.h
+++ b/gtsam/nonlinear/Expression-inl.h
@@ -19,7 +19,7 @@
 
 #pragma once
 
-#include <gtsam/nonlinear/ExpressionNode.h>
+#include <gtsam/nonlinear/internal/ExpressionNode.h>
 
 #include <boost/tuple/tuple.hpp>
 #include <boost/range/adaptor/map.hpp>
diff --git a/gtsam/nonlinear/CallRecord.h b/gtsam/nonlinear/internal/CallRecord.h
similarity index 100%
rename from gtsam/nonlinear/CallRecord.h
rename to gtsam/nonlinear/internal/CallRecord.h
diff --git a/gtsam/nonlinear/ExecutionTrace.h b/gtsam/nonlinear/internal/ExecutionTrace.h
similarity index 100%
rename from gtsam/nonlinear/ExecutionTrace.h
rename to gtsam/nonlinear/internal/ExecutionTrace.h
diff --git a/gtsam/nonlinear/ExpressionNode.h b/gtsam/nonlinear/internal/ExpressionNode.h
similarity index 99%
rename from gtsam/nonlinear/ExpressionNode.h
rename to gtsam/nonlinear/internal/ExpressionNode.h
index 1cbfd488c..40b071b00 100644
--- a/gtsam/nonlinear/ExpressionNode.h
+++ b/gtsam/nonlinear/internal/ExpressionNode.h
@@ -19,8 +19,8 @@
 
 #pragma once
 
-#include <gtsam/nonlinear/ExecutionTrace.h>
-#include <gtsam/nonlinear/CallRecord.h>
+#include <gtsam/nonlinear/internal/ExecutionTrace.h>
+#include <gtsam/nonlinear/internal/CallRecord.h>
 #include <gtsam/nonlinear/Values.h>
 
 // template meta-programming headers
diff --git a/gtsam/nonlinear/tests/testCallRecord.cpp b/gtsam/nonlinear/tests/testCallRecord.cpp
index 376ef56e4..09099ba1b 100644
--- a/gtsam/nonlinear/tests/testCallRecord.cpp
+++ b/gtsam/nonlinear/tests/testCallRecord.cpp
@@ -18,7 +18,7 @@
  * @brief unit tests for CallRecord class
  */
 
-#include <gtsam/nonlinear/CallRecord.h>
+#include <gtsam/nonlinear/internal/CallRecord.h>
 #include <gtsam/base/Matrix.h>
 #include <gtsam/base/Testable.h>
 
diff --git a/gtsam/nonlinear/tests/testExecutionTrace.cpp b/gtsam/nonlinear/tests/testExecutionTrace.cpp
index 5d0f33966..731f69816 100644
--- a/gtsam/nonlinear/tests/testExecutionTrace.cpp
+++ b/gtsam/nonlinear/tests/testExecutionTrace.cpp
@@ -16,7 +16,7 @@
  * @brief unit tests for Expression internals
  */
 
-#include <gtsam/nonlinear/ExecutionTrace.h>
+#include <gtsam/nonlinear/internal/ExecutionTrace.h>
 #include <gtsam/geometry/Point2.h>
 
 #include <CppUnitLite/TestHarness.h>