diff --git a/gtsam/nonlinear/Marginals.h b/gtsam/nonlinear/Marginals.h
index 028545d01..3c5aa9cab 100644
--- a/gtsam/nonlinear/Marginals.h
+++ b/gtsam/nonlinear/Marginals.h
@@ -121,7 +121,7 @@ public:
 
   /** Optimize the bayes tree */
   VectorValues optimize() const;
-            
+
 protected:
   
   /** Compute the Bayes Tree as a helper function to the constructor */
diff --git a/gtsam/nonlinear/PriorFactor.h b/gtsam/nonlinear/PriorFactor.h
index c745f7bd9..a490162ac 100644
--- a/gtsam/nonlinear/PriorFactor.h
+++ b/gtsam/nonlinear/PriorFactor.h
@@ -94,7 +94,6 @@ namespace gtsam {
     Vector evaluateError(const T& x, boost::optional<Matrix&> H = boost::none) const override {
       if (H) (*H) = Matrix::Identity(traits<T>::GetDimension(x),traits<T>::GetDimension(x));
       // manifold equivalent of z-x -> Local(x,z)
-      // TODO(ASL) Add Jacobians.
       return -traits<T>::Local(x, prior_);
     }
 
diff --git a/gtsam/slam/tests/testPriorFactor.cpp b/gtsam/slam/tests/testPriorFactor.cpp
index 2dc083cb2..d1a60e346 100644
--- a/gtsam/slam/tests/testPriorFactor.cpp
+++ b/gtsam/slam/tests/testPriorFactor.cpp
@@ -5,12 +5,16 @@
  * @date   Nov 4, 2014
  */
 
-#include <gtsam/base/Vector.h>
-#include <gtsam/nonlinear/PriorFactor.h>
 #include <CppUnitLite/TestHarness.h>
+#include <gtsam/base/Vector.h>
+#include <gtsam/navigation/ImuBias.h>
+#include <gtsam/nonlinear/PriorFactor.h>
+#include <gtsam/nonlinear/factorTesting.h>
 
 using namespace std;
+using namespace std::placeholders;
 using namespace gtsam;
+using namespace imuBias;
 
 /* ************************************************************************* */
 
@@ -23,16 +27,44 @@ TEST(PriorFactor, ConstructorScalar) {
 // Constructor vector3
 TEST(PriorFactor, ConstructorVector3) {
   SharedNoiseModel model = noiseModel::Isotropic::Sigma(3, 1.0);
-  PriorFactor<Vector3> factor(1, Vector3(1,2,3), model);
+  PriorFactor<Vector3> factor(1, Vector3(1, 2, 3), model);
 }
 
 // Constructor dynamic sized vector
 TEST(PriorFactor, ConstructorDynamicSizeVector) {
-  Vector v(5); v << 1, 2, 3, 4, 5;
+  Vector v(5);
+  v << 1, 2, 3, 4, 5;
   SharedNoiseModel model = noiseModel::Isotropic::Sigma(5, 1.0);
   PriorFactor<Vector> factor(1, v, model);
 }
 
+Vector callEvaluateError(const PriorFactor<ConstantBias>& factor,
+                         const ConstantBias& bias) {
+  return factor.evaluateError(bias);
+}
+
+// Test for imuBias::ConstantBias
+TEST(PriorFactor, ConstantBias) {
+  Vector3 biasAcc(1, 2, 3);
+  Vector3 biasGyro(0.1, 0.2, 0.3);
+  ConstantBias bias(biasAcc, biasGyro);
+
+  PriorFactor<ConstantBias> factor(1, bias,
+                                   noiseModel::Isotropic::Sigma(6, 0.1));
+  Values values;
+  values.insert(1, bias);
+
+  EXPECT_DOUBLES_EQUAL(0.0, factor.error(values), 1e-8);
+  EXPECT_CORRECT_FACTOR_JACOBIANS(factor, values, 1e-7, 1e-5);
+
+  ConstantBias incorrectBias(
+      (Vector6() << 1.1, 2.1, 3.1, 0.2, 0.3, 0.4).finished());
+  values.clear();
+  values.insert(1, incorrectBias);
+  EXPECT_DOUBLES_EQUAL(3.0, factor.error(values), 1e-8);
+  EXPECT_CORRECT_FACTOR_JACOBIANS(factor, values, 1e-7, 1e-5);
+}
+
 /* ************************************************************************* */
 int main() {
   TestResult tr;