diff --git a/corelib/src/optimizer/gtsam/GravityFactor.h b/corelib/src/optimizer/gtsam/GravityFactor.h
index fb2b3ee..917b6e0 100644
--- a/corelib/src/optimizer/gtsam/GravityFactor.h
+++ b/corelib/src/optimizer/gtsam/GravityFactor.h
@@ -25,6 +25,7 @@
 #pragma once
 
 #include <gtsam/nonlinear/NonlinearFactor.h>
+#include <gtsam/nonlinear/NoiseModelFactorN.h>
 #include <gtsam/geometry/Pose3.h>
 #include <gtsam/geometry/Unit3.h>