diff --git a/matlab/gtsam_examples/IMUKittiExampleGPS.m b/matlab/gtsam_examples/IMUKittiExampleGPS.m
index c80b6ec3e..530c3382c 100755
--- a/matlab/gtsam_examples/IMUKittiExampleGPS.m
+++ b/matlab/gtsam_examples/IMUKittiExampleGPS.m
@@ -99,7 +99,7 @@ for measurementIndex = firstGPSPose:length(GPS_data)
     newFactors.add(ImuFactor( ...
       currentPoseKey-1, currentVelKey-1, ...
       currentPoseKey, currentVelKey, ...
-      currentBiasKey, currentSummarizedMeasurement));
+      currentBiasKey-1, currentSummarizedMeasurement));
 
     % Bias evolution as given in the IMU metadata
     newFactors.add(BetweenFactorConstantBias(currentBiasKey-1, currentBiasKey, imuBias.ConstantBias(zeros(3,1), zeros(3,1)), ...