diff --git a/gtsam/navigation/tests/testImuFactor.cpp b/gtsam/navigation/tests/testImuFactor.cpp
index 01b331e42..daa8d0b26 100644
--- a/gtsam/navigation/tests/testImuFactor.cpp
+++ b/gtsam/navigation/tests/testImuFactor.cpp
@@ -155,7 +155,7 @@ bool MonteCarlo(const PreintegratedImuMeasurements& pim,
   Q.setZero();
   for (size_t i = 0; i < N; i++) {
     Vector9 xi = samples.col(i);
-     xi -= sampleMean;
+    xi -= sampleMean;
     Q += xi * xi.transpose() / (N - 1);
   }