diff --git a/gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h b/gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h
index 39af8f27e..28895046a 100644
--- a/gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h
+++ b/gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h
@@ -110,7 +110,7 @@ public:
   }
 
   /// Get results of latest isam2 update
-  const ISAM2Result getISAM2Result() const{ return isamResult_; }
+  const ISAM2Result& ISAM2Result() const {return isamResult_;}
 
 protected:
   /** An iSAM2 object used to perform inference. The smoother lag is controlled