diff --git a/gtsam/nonlinear/GradientDescentOptimizer.h b/gtsam/nonlinear/GradientDescentOptimizer.h
index 659aff68c..5caef0957 100644
--- a/gtsam/nonlinear/GradientDescentOptimizer.h
+++ b/gtsam/nonlinear/GradientDescentOptimizer.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <gtsam/base/manifold.h>
+#include <gtsam/base/Manifold.h>
 #include <gtsam/nonlinear/NonlinearOptimizer.h>
 
 namespace gtsam {