diff --git a/gtsam/nonlinear/nonlinear.i b/gtsam/nonlinear/nonlinear.i
index ef2a7218d..c13defbad 100644
--- a/gtsam/nonlinear/nonlinear.i
+++ b/gtsam/nonlinear/nonlinear.i
@@ -731,7 +731,7 @@ virtual class BatchFixedLagSmoother : gtsam::FixedLagSmoother {
   VALUE calculateEstimate(size_t key) const;
 };
 
-#include <gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h>
+#include <gtsam/nonlinear/IncrementalFixedLagSmoother.h>
 virtual class IncrementalFixedLagSmoother : gtsam::FixedLagSmoother {
   IncrementalFixedLagSmoother();
   IncrementalFixedLagSmoother(double smootherLag);