diff --git a/frc971/control_loops/quaternion_utils.h b/frc971/control_loops/quaternion_utils.h
index 3e40e3f4..c2c854c 100644
--- a/frc971/control_loops/quaternion_utils.h
+++ b/frc971/control_loops/quaternion_utils.h
@@ -8,19 +8,17 @@
 
 namespace frc971::controls {
 
-// Function to compute the quaternion average of a bunch of quaternions. Each
-// column in the input matrix is a quaternion (optionally scaled by it's
-// weight).
-template <int SM>
-inline Eigen::Matrix<double, 4, 1> QuaternionMean(
-    Eigen::Matrix<double, 4, SM> input) {
+// Helper function to extract mean quaternion from A*A^T of quaternion list
+// This allows us to support multiple formats of the input quaternion list
+inline Eigen::Matrix<double, 4, 1> ExtractQuaternionMean(
+    Eigen::Matrix<double, 4, 4> input) {
   // Algorithm to compute the average of a bunch of quaternions:
-  // http://www.acsu.buffalo.edu/~johnc/ave_quat07.pdf
-
-  Eigen::Matrix<double, 4, 4> m = input * input.transpose();
+  //  http://www.acsu.buffalo.edu/~johnc/ave_quat07.pdf
+  // See also:
+  //  https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070017872.pdf
 
   Eigen::EigenSolver<Eigen::Matrix<double, 4, 4>> solver;
-  solver.compute(m);
+  solver.compute(input);
 
   Eigen::EigenSolver<Eigen::Matrix<double, 4, 4>>::EigenvectorsType
       eigenvectors = solver.eigenvectors();
@@ -47,6 +45,37 @@
   return eigenvectors.col(max_index).real().normalized();
 }
 
+// Function to compute the quaternion average of a bunch of quaternions. Each
+// column in the 4xN input Matrix is a quaternion (optionally scaled by it's
+// weight).
+template <int N>
+inline Eigen::Matrix<double, 4, 1> QuaternionMean(
+    Eigen::Matrix<double, 4, N> quaternions) {
+  Eigen::Matrix<double, 4, 4> m = quaternions * quaternions.transpose();
+
+  return ExtractQuaternionMean(m);
+}
+
+// Function to compute the quaternion average of a bunch of quaternions.
+// This allows for passing in a variable size list (vector) of quaternions
+
+// For reference (since I've been bitten by it):
+// Eigen::Quaternion stores and prints coefficients as [x, y, z, w]
+// and initializes using a Vector4d in this order, BUT
+// initializes with scalars as Eigen::Quaternion{w, x, y, z}
+inline Eigen::Vector4d QuaternionMean(
+    std::vector<Eigen::Vector4d> quaternion_list) {
+  CHECK(quaternion_list.size() != 0)
+      << "Must have at least one quaternion to compute an average!";
+
+  Eigen::Matrix<double, 4, 4> m = Eigen::Matrix4d::Zero();
+  for (Eigen::Vector4d quaternion : quaternion_list) {
+    m += quaternion * quaternion.transpose();
+  }
+
+  return Eigen::Vector4d(ExtractQuaternionMean(m));
+}
+
 // Converts from a quaternion to a rotation vector, where the rotation vector's
 // direction represents the axis to rotate around and its magnitude represents
 // the number of radians to rotate.
@@ -74,7 +103,7 @@
 inline Eigen::Vector4d QuaternionDerivative(Eigen::Vector3d omega,
                                             const Eigen::Vector4d &q_matrix) {
   // See https://www.ashwinnarayan.com/post/how-to-integrate-quaternions/ for
-  // another resource on quaternion integration and derivitives.
+  // another resource on quaternion integration and derivatives.
   Eigen::Quaternion<double> q(q_matrix);
 
   Eigen::Quaternion<double> omega_q;
diff --git a/frc971/control_loops/quaternion_utils_test.cc b/frc971/control_loops/quaternion_utils_test.cc
index 2eaeaa0..63f4507 100644
--- a/frc971/control_loops/quaternion_utils_test.cc
+++ b/frc971/control_loops/quaternion_utils_test.cc
@@ -17,6 +17,7 @@
 // return the original quaternion.
 TEST(DownEstimatorTest, QuaternionMean) {
   Eigen::Matrix<double, 4, 7> vectors;
+  std::vector<Eigen::Vector4d> quaternion_list;
   vectors.col(0) << 0, 0, 0, 1;
   for (int i = 0; i < 3; ++i) {
     Eigen::Matrix<double, 4, 1> perturbation;
@@ -29,6 +30,7 @@
 
   for (int i = 0; i < 7; ++i) {
     vectors.col(i).normalize();
+    quaternion_list.push_back(Eigen::Vector4d(vectors.col(i)));
   }
 
   Eigen::Matrix<double, 4, 1> mean = QuaternionMean(vectors);
@@ -36,6 +38,15 @@
   for (int i = 0; i < 4; ++i) {
     EXPECT_NEAR(mean(i, 0), vectors(i, 0), 0.001) << ": Failed on index " << i;
   }
+
+  // Test version of code that passes in a vector of quaternions
+  mean = QuaternionMean(quaternion_list);
+
+  for (int i = 0; i < 4; ++i) {
+    EXPECT_NEAR(mean(i, 0), quaternion_list[0](i, 0), 0.001)
+        << ": Failed on index " << i << " with mean = " << mean
+        << " and quat_list = " << quaternion_list[0];
+  }
 }
 
 // Tests that ToRotationVectorFromQuaternion works for a 0 rotation.