diff --git a/gtsam/base/Lie.h b/gtsam/base/Lie.h
index b6ec6a724..bbed26992 100644
--- a/gtsam/base/Lie.h
+++ b/gtsam/base/Lie.h
@@ -160,17 +160,6 @@ struct LieGroup {
     if (H2) *H2 = D_v_h;
     return v;
   }
-
-  // Functor for transforming covariance of Class
-  class TransformCovariance
-  {
-  private:
-    typename Class::Jacobian adjointMap_;
-  public:
-    explicit TransformCovariance(const Class &X) : adjointMap_{X.AdjointMap()} {}
-    typename Class::Jacobian operator()(const typename Class::Jacobian &covariance)
-    { return adjointMap_ * covariance * adjointMap_.transpose(); }
-  };
 };
 
 /// tag to assert a type is a Lie group
@@ -346,6 +335,21 @@ T interpolate(const T& X, const T& Y, double t) {
   return traits<T>::Compose(X, traits<T>::Expmap(t * traits<T>::Logmap(traits<T>::Between(X, Y))));
 }
 
+/**
+ * Functor for transforming covariance of T.
+ * T needs to satisfy the Lie group concept.
+ */
+template<class T>
+class TransformCovariance
+{
+private:
+  typename T::Jacobian adjointMap_;
+public:
+  explicit TransformCovariance(const T &X) : adjointMap_{X.AdjointMap()} {}
+  typename T::Jacobian operator()(const typename T::Jacobian &covariance)
+  { return adjointMap_ * covariance * adjointMap_.transpose(); }
+};
+
 } // namespace gtsam
 
 /**
diff --git a/gtsam/geometry/tests/testPose2.cpp b/gtsam/geometry/tests/testPose2.cpp
index 81f097bd9..3d821502d 100644
--- a/gtsam/geometry/tests/testPose2.cpp
+++ b/gtsam/geometry/tests/testPose2.cpp
@@ -846,7 +846,7 @@ TEST(Pose2 , TransformCovariance3) {
   // rotate
   {
     auto cov = FullCovarianceFromSigmas<Pose2>({0.1, 0.3, 0.7});
-    auto transformed = Pose2::TransformCovariance{{0., 0., 90 * degree}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{0., 0., 90 * degree}}(cov);
     // interchange x and y axes
     EXPECT(assert_equal(
       Vector3{cov(1, 1), cov(0, 0), cov(2, 2)},
@@ -859,7 +859,7 @@ TEST(Pose2 , TransformCovariance3) {
   // translate along x with uncertainty in x
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose2>(0, 0.1);
-    auto transformed = Pose2::TransformCovariance{{20., 0., 0.}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{20., 0., 0.}}(cov);
     // No change
     EXPECT(assert_equal(cov, transformed));
   }
@@ -867,7 +867,7 @@ TEST(Pose2 , TransformCovariance3) {
   // translate along x with uncertainty in y
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose2>(1, 0.1);
-    auto transformed = Pose2::TransformCovariance{{20., 0., 0.}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{20., 0., 0.}}(cov);
     // No change
     EXPECT(assert_equal(cov, transformed));
   }
@@ -875,7 +875,7 @@ TEST(Pose2 , TransformCovariance3) {
   // translate along x with uncertainty in theta
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose2>(2, 0.1);
-    auto transformed = Pose2::TransformCovariance{{20., 0., 0.}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{20., 0., 0.}}(cov);
     EXPECT(assert_equal(
       Vector3{0., 0.1 * 0.1 * 20. * 20., 0.1 * 0.1},
       Vector3{transformed.diagonal()}));
@@ -887,7 +887,7 @@ TEST(Pose2 , TransformCovariance3) {
   // rotate and translate along x with uncertainty in x
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose2>(0, 0.1);
-    auto transformed = Pose2::TransformCovariance{{20., 0., 90 * degree}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{20., 0., 90 * degree}}(cov);
     // interchange x and y axes
     EXPECT(assert_equal(
       Vector3{cov(1, 1), cov(0, 0), cov(2, 2)},
@@ -900,7 +900,7 @@ TEST(Pose2 , TransformCovariance3) {
   // rotate and translate along x with uncertainty in theta
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose2>(2, 0.1);
-    auto transformed = Pose2::TransformCovariance{{20., 0., 90 * degree}}(cov);
+    auto transformed = TransformCovariance<Pose2>{{20., 0., 90 * degree}}(cov);
     EXPECT(assert_equal(
       Vector3{0., 0.1 * 0.1 * 20. * 20., 0.1 * 0.1},
       Vector3{transformed.diagonal()}));
diff --git a/gtsam/geometry/tests/testPose3.cpp b/gtsam/geometry/tests/testPose3.cpp
index fc702d3b3..fedd47620 100644
--- a/gtsam/geometry/tests/testPose3.cpp
+++ b/gtsam/geometry/tests/testPose3.cpp
@@ -888,7 +888,7 @@ TEST(Pose3, TransformCovariance6MapTo2d) {
   Vector3 s2{0.1, 0.3, 0.7};
   Pose2 p2{1.1, 1.5, 31. * degree};
   auto cov2 = FullCovarianceFromSigmas<Pose2>(s2);
-  auto transformed2 = Pose2::TransformCovariance{p2}(cov2);
+  auto transformed2 = TransformCovariance<Pose2>{p2}(cov2);
 
   auto match_cov3_to_cov2 = [&](int spatial_axis0, int spatial_axis1, int r_axis,
                                 const Pose2::Jacobian &cov2, const Pose3::Jacobian &cov3) -> void
@@ -904,21 +904,21 @@ TEST(Pose3, TransformCovariance6MapTo2d) {
   // rotate around x axis
   {
     auto cov3 = FullCovarianceFromSigmas<Pose3>((Vector6{} << s2(2), 0., 0., 0., s2(0), s2(1)).finished());
-    auto transformed3 = Pose3::TransformCovariance{{Rot3::RzRyRx(p2.theta(), 0., 0.), {0., p2.x(), p2.y()}}}(cov3);
+    auto transformed3 = TransformCovariance<Pose3>{{Rot3::RzRyRx(p2.theta(), 0., 0.), {0., p2.x(), p2.y()}}}(cov3);
     match_cov3_to_cov2(4, 5, 0, transformed2, transformed3);
   }
 
   // rotate around y axis
   {
     auto cov3 = FullCovarianceFromSigmas<Pose3>((Vector6{} << 0., s2(2), 0., s2(1), 0., s2(0)).finished());
-    auto transformed3 = Pose3::TransformCovariance{{Rot3::RzRyRx(0., p2.theta(), 0.), {p2.y(), 0., p2.x()}}}(cov3);
+    auto transformed3 = TransformCovariance<Pose3>{{Rot3::RzRyRx(0., p2.theta(), 0.), {p2.y(), 0., p2.x()}}}(cov3);
     match_cov3_to_cov2(5, 3, 1, transformed2, transformed3);
   }
 
   // rotate around z axis
   {
     auto cov3 = FullCovarianceFromSigmas<Pose3>((Vector6{} << 0., 0., s2(2), s2(0), s2(1), 0.).finished());
-    auto transformed3 = Pose3::TransformCovariance{{Rot3::RzRyRx(0., 0., p2.theta()), {p2.x(), p2.y(), 0.}}}(cov3);
+    auto transformed3 = TransformCovariance<Pose3>{{Rot3::RzRyRx(0., 0., p2.theta()), {p2.x(), p2.y(), 0.}}}(cov3);
     match_cov3_to_cov2(3, 4, 2, transformed2, transformed3);
   }
 }
@@ -932,7 +932,7 @@ TEST(Pose3, TransformCovariance6) {
   // rotate 90 around z axis and then 90 around y axis
   {
     auto cov = FullCovarianceFromSigmas<Pose3>((Vector6{} << 0.1, 0.2, 0.3, 0.5, 0.7, 1.1).finished());
-    auto transformed = Pose3::TransformCovariance{{Rot3::RzRyRx(0., 90 * degree, 90 * degree), {0., 0., 0.}}}(cov);
+    auto transformed = TransformCovariance<Pose3>{{Rot3::RzRyRx(0., 90 * degree, 90 * degree), {0., 0., 0.}}}(cov);
     // x from y, y from z, z from x
     EXPECT(assert_equal(
       (Vector6{} << cov(1, 1), cov(2, 2), cov(0, 0), cov(4, 4), cov(5, 5), cov(3, 3)).finished(),
@@ -947,7 +947,7 @@ TEST(Pose3, TransformCovariance6) {
   // translate along the x axis with uncertainty in roty and rotz
   {
     auto cov = TwoVariableCovarianceFromSigmas<Pose3>(1, 2, 0.7, 0.3);
-    auto transformed = Pose3::TransformCovariance{{Rot3::RzRyRx(0., 0., 0.), {20., 0., 0.}}}(cov);
+    auto transformed = TransformCovariance<Pose3>{{Rot3::RzRyRx(0., 0., 0.), {20., 0., 0.}}}(cov);
     // The uncertainty in roty and rotz causes off-diagonal covariances
     EXPECT(assert_equal(0.7 * 0.7 * 20., transformed(5, 1)));
     EXPECT(assert_equal(0.7 * 0.7 * 20. * 20., transformed(5, 5)));
@@ -961,7 +961,7 @@ TEST(Pose3, TransformCovariance6) {
   // rotate around x axis and translate along the x axis with uncertainty in rotx
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose3>(0, 0.1);
-    auto transformed = Pose3::TransformCovariance{{Rot3::RzRyRx(90 * degree, 0., 0.), {20., 0., 0.}}}(cov);
+    auto transformed = TransformCovariance<Pose3>{{Rot3::RzRyRx(90 * degree, 0., 0.), {20., 0., 0.}}}(cov);
     // No change
     EXPECT(assert_equal(cov, transformed));
   }
@@ -969,7 +969,7 @@ TEST(Pose3, TransformCovariance6) {
   // rotate around x axis and translate along the x axis with uncertainty in roty
   {
     auto cov = SingleVariableCovarianceFromSigma<Pose3>(1, 0.1);
-    auto transformed = Pose3::TransformCovariance{{Rot3::RzRyRx(90 * degree, 0., 0.), {20., 0., 0.}}}(cov);
+    auto transformed = TransformCovariance<Pose3>{{Rot3::RzRyRx(90 * degree, 0., 0.), {20., 0., 0.}}}(cov);
     // Uncertainty is spread to other dimensions.
     EXPECT(assert_equal(
       (Vector6{} << 0., 0., 0.1 * 0.1, 0., 0.1 * 0.1 * 20. * 20., 0.).finished(),