diff --git a/gtsam/base/Matrix.cpp b/gtsam/base/Matrix.cpp
index e0cb055b7..cde1ba2ef 100644
--- a/gtsam/base/Matrix.cpp
+++ b/gtsam/base/Matrix.cpp
@@ -616,7 +616,7 @@ Matrix inverse_square_root(const Matrix& A) {
 	Matrix R = RtR(A);
 	Matrix inv = eye(A.rows());
 	R.triangularView<Eigen::Upper>().solveInPlace<Eigen::OnTheRight>(inv);
-	return inv;
+	return inv.transpose();
 }
 
 /* ************************************************************************* */
diff --git a/gtsam/base/tests/testMatrix.cpp b/gtsam/base/tests/testMatrix.cpp
index be46b3ddf..a6b1960dd 100644
--- a/gtsam/base/tests/testMatrix.cpp
+++ b/gtsam/base/tests/testMatrix.cpp
@@ -877,12 +877,12 @@ TEST( matrix, inverse_square_root )
 			-0.0171880,-0.0101952, 0.0054906, 0.0892453, -0.0059468,
 			0.0028726, 0.0175868, 0.0047064, -0.0059468, 0.0816517);
 
-	expected = trans(Matrix_(5, 5,
+	expected = Matrix_(5, 5,
 			3.567126953241796, 0.000000000000000, 0.000000000000000, 0.000000000000000, 0.000000000000000,
 			-0.590030436566913, 3.362022286742925, 0.000000000000000, 0.000000000000000, 0.000000000000000,
 			0.618207860252376, -0.168166020746503, 3.253086082942785, 0.000000000000000, 0.000000000000000,
 			0.683045380655496, 0.283773848115276, -0.099969232183396, 3.433537147891568, 0.000000000000000,
-			-0.006740136923185, -0.669325697387650, -0.169716689114923, 0.171493059476284, 3.583921085468937));
+			-0.006740136923185, -0.669325697387650, -0.169716689114923, 0.171493059476284, 3.583921085468937);
 	EQUALITY(expected, inverse_square_root(M));
 
 }