diff --git a/tachyon/math/elliptic_curves/short_weierstrass/affine_point_unittest.cc b/tachyon/math/elliptic_curves/short_weierstrass/affine_point_unittest.cc
index 80427ab9ee..992fd3aae3 100644
--- a/tachyon/math/elliptic_curves/short_weierstrass/affine_point_unittest.cc
+++ b/tachyon/math/elliptic_curves/short_weierstrass/affine_point_unittest.cc
@@ -177,7 +177,7 @@ TEST_F(AffinePointTest, Copyable) {
 
 TEST_F(AffinePointTest, JsonValueConverter) {
   test::AffinePoint expected_point(GF7(1), GF7(2));
-  std::string expected_json = R"({"x":"0x1","y":"0x2"})";
+  std::string expected_json = R"({"x":1,"y":2})";
 
   test::AffinePoint p;
   std::string error;
diff --git a/tachyon/math/elliptic_curves/short_weierstrass/jacobian_point_unittest.cc b/tachyon/math/elliptic_curves/short_weierstrass/jacobian_point_unittest.cc
index 776a543f35..b8800eeaca 100644
--- a/tachyon/math/elliptic_curves/short_weierstrass/jacobian_point_unittest.cc
+++ b/tachyon/math/elliptic_curves/short_weierstrass/jacobian_point_unittest.cc
@@ -253,7 +253,7 @@ TEST_F(JacobianPointTest, Copyable) {
 
 TEST_F(JacobianPointTest, JsonValueConverter) {
   test::JacobianPoint expected_point(GF7(1), GF7(2), GF7(3));
-  std::string expected_json = R"({"x":"0x1","y":"0x2","z":"0x3"})";
+  std::string expected_json = R"({"x":1,"y":2,"z":3})";
 
   test::JacobianPoint p;
   std::string error;
diff --git a/tachyon/math/elliptic_curves/short_weierstrass/point_xyzz_unittest.cc b/tachyon/math/elliptic_curves/short_weierstrass/point_xyzz_unittest.cc
index 61e38f568e..b9896723aa 100644
--- a/tachyon/math/elliptic_curves/short_weierstrass/point_xyzz_unittest.cc
+++ b/tachyon/math/elliptic_curves/short_weierstrass/point_xyzz_unittest.cc
@@ -256,7 +256,7 @@ TEST_F(PointXYZZTest, Copyable) {
 
 TEST_F(PointXYZZTest, JsonValueConverter) {
   test::PointXYZZ expected_point(GF7(1), GF7(2), GF7(3), GF7(4));
-  std::string expected_json = R"({"x":"0x1","y":"0x2","zz":"0x3","zzz":"0x4"})";
+  std::string expected_json = R"({"x":1,"y":2,"zz":3,"zzz":4})";
 
   test::PointXYZZ p;
   std::string error;
diff --git a/tachyon/math/elliptic_curves/short_weierstrass/projective_point_unittest.cc b/tachyon/math/elliptic_curves/short_weierstrass/projective_point_unittest.cc
index 4370b4226f..669ece2b85 100644
--- a/tachyon/math/elliptic_curves/short_weierstrass/projective_point_unittest.cc
+++ b/tachyon/math/elliptic_curves/short_weierstrass/projective_point_unittest.cc
@@ -256,7 +256,7 @@ TEST_F(ProjectivePointTest, Copyable) {
 
 TEST_F(ProjectivePointTest, JsonValueConverter) {
   test::ProjectivePoint expected_point(GF7(1), GF7(2), GF7(3));
-  std::string expected_json = R"({"x":"0x1","y":"0x2","z":"0x3"})";
+  std::string expected_json = R"({"x":1,"y":2,"z":3})";
 
   test::ProjectivePoint p;
   std::string error;
diff --git a/tachyon/math/finite_fields/cubic_extension_field_unittest.cc b/tachyon/math/finite_fields/cubic_extension_field_unittest.cc
index 39d5c7d5f8..4b35afe4d1 100644
--- a/tachyon/math/finite_fields/cubic_extension_field_unittest.cc
+++ b/tachyon/math/finite_fields/cubic_extension_field_unittest.cc
@@ -181,7 +181,7 @@ TEST_F(CubicExtensionFieldTest, MultiplicativeGroupOperators) {
 
 TEST_F(CubicExtensionFieldTest, JsonValueConverter) {
   GF7_3 expected_point(GF7(1), GF7(2), GF7(3));
-  std::string expected_json = R"({"c0":"0x1","c1":"0x2","c2":"0x3"})";
+  std::string expected_json = R"({"c0":1,"c1":2,"c2":3})";
 
   GF7_3 p;
   std::string error;
diff --git a/tachyon/math/finite_fields/prime_field_base.h b/tachyon/math/finite_fields/prime_field_base.h
index e56d0cff06..1de8ca4b2a 100644
--- a/tachyon/math/finite_fields/prime_field_base.h
+++ b/tachyon/math/finite_fields/prime_field_base.h
@@ -222,6 +222,7 @@ template <typename T>
 class RapidJsonValueConverter<
     T, std::enable_if_t<std::is_base_of_v<math::PrimeFieldBase<T>, T>>> {
  public:
+  using value_type = typename T::value_type;
   using BigInt = typename T::BigIntTy;
 
   static bool s_allow_value_greater_than_or_equal_to_modulus;
@@ -231,21 +232,32 @@ class RapidJsonValueConverter<
   static rapidjson::Value From(const T& value, Allocator& allocator) {
     if constexpr (T::Config::kUseMontgomery) {
       if (s_is_in_montgomery) {
-        return RapidJsonValueConverter<BigInt>::From(value.value(), allocator);
+        return RapidJsonValueConverter<value_type>::From(value.value(),
+                                                         allocator);
       }
     }
-    return RapidJsonValueConverter<BigInt>::From(value.ToBigInt(), allocator);
+    if constexpr (T::Config::kModulusBits <= 32) {
+      if constexpr (T::Config::kUseMontgomery) {
+        return RapidJsonValueConverter<uint32_t>::From(
+            T::Config::FromMontgomery(value.value()), allocator);
+      } else {
+        return RapidJsonValueConverter<uint32_t>::From(value.value(),
+                                                       allocator);
+      }
+    } else {
+      return RapidJsonValueConverter<BigInt>::From(value.ToBigInt(), allocator);
+    }
   }
 
   static bool To(const rapidjson::Value& json_value, std::string_view key,
                  T* value, std::string* error) {
-    BigInt v;
-    if (!RapidJsonValueConverter<BigInt>::To(json_value, key, &v, error))
+    value_type v;
+    if (!RapidJsonValueConverter<value_type>::To(json_value, key, &v, error))
       return false;
 
     if (s_allow_value_greater_than_or_equal_to_modulus) {
-      if (v >= BigInt(T::Config::kModulus)) {
-        v = v.Mod(BigInt(T::Config::kModulus));
+      if (v >= T::Config::kModulus) {
+        v %= T::Config::kModulus;
       }
     }
     if constexpr (T::Config::kUseMontgomery) {
@@ -254,7 +266,7 @@ class RapidJsonValueConverter<
         return true;
       }
     }
-    *value = T::FromBigInt(v);
+    *value = T(v);
     return true;
   }
 };
diff --git a/tachyon/math/finite_fields/quadratic_extension_field_unittest.cc b/tachyon/math/finite_fields/quadratic_extension_field_unittest.cc
index 09418c40f7..ee7be6c67c 100644
--- a/tachyon/math/finite_fields/quadratic_extension_field_unittest.cc
+++ b/tachyon/math/finite_fields/quadratic_extension_field_unittest.cc
@@ -193,7 +193,7 @@ TEST(CyclotomicInverseTest, FastCyclotomicInverse) {
 
 TEST_F(QuadraticExtensionFieldTest, JsonValueConverter) {
   GF7_2 expected_point(GF7(1), GF7(2));
-  std::string expected_json = R"({"c0":"0x1","c1":"0x2"})";
+  std::string expected_json = R"({"c0":1,"c1":2})";
 
   GF7_2 p;
   std::string error;
diff --git a/tachyon/math/geometry/point2_unittest.cc b/tachyon/math/geometry/point2_unittest.cc
index f518a42cf8..4584e4b85d 100644
--- a/tachyon/math/geometry/point2_unittest.cc
+++ b/tachyon/math/geometry/point2_unittest.cc
@@ -55,7 +55,7 @@ TEST(Point2Test, Copyable) {
 
 TEST(Point2Test, JsonValueConverter) {
   Point2GF7 expected_point(GF7(1), GF7(2));
-  std::string expected_json = R"({"x":"0x1","y":"0x2"})";
+  std::string expected_json = R"({"x":1,"y":2})";
 
   Point2GF7 p;
   std::string error;
diff --git a/tachyon/math/geometry/point3_unittest.cc b/tachyon/math/geometry/point3_unittest.cc
index bc4d11804f..6f91731d2c 100644
--- a/tachyon/math/geometry/point3_unittest.cc
+++ b/tachyon/math/geometry/point3_unittest.cc
@@ -57,7 +57,7 @@ TEST(Point3Test, Copyable) {
 
 TEST(Point3Test, JsonValueConverter) {
   Point3GF7 expected_point(GF7(1), GF7(2), GF7(3));
-  std::string expected_json = R"({"x":"0x1","y":"0x2","z":"0x3"})";
+  std::string expected_json = R"({"x":1,"y":2,"z":3})";
 
   Point3GF7 p;
   std::string error;
diff --git a/tachyon/math/geometry/point4_unittest.cc b/tachyon/math/geometry/point4_unittest.cc
index 43acd10dd6..a1b148abbb 100644
--- a/tachyon/math/geometry/point4_unittest.cc
+++ b/tachyon/math/geometry/point4_unittest.cc
@@ -61,7 +61,7 @@ TEST(Point4Test, Copyable) {
 
 TEST(Point4Test, JsonValueConverter) {
   Point4GF7 expected_point(GF7(1), GF7(2), GF7(3), GF7(4));
-  std::string expected_json = R"({"x":"0x1","y":"0x2","z":"0x3","w":"0x4"})";
+  std::string expected_json = R"({"x":1,"y":2,"z":3,"w":4})";
 
   Point4GF7 p;
   std::string error;
diff --git a/tachyon/math/polynomials/univariate/univariate_dense_polynomial_unittest.cc b/tachyon/math/polynomials/univariate/univariate_dense_polynomial_unittest.cc
index f73296d262..178a6e77cd 100644
--- a/tachyon/math/polynomials/univariate/univariate_dense_polynomial_unittest.cc
+++ b/tachyon/math/polynomials/univariate/univariate_dense_polynomial_unittest.cc
@@ -399,7 +399,7 @@ TEST_F(UnivariateDensePolynomialTest, Hash) {
 TEST_F(UnivariateDensePolynomialTest, JsonValueConverter) {
   Poly expected_poly(Coeffs({GF7(1), GF7(2), GF7(3), GF7(4), GF7(5)}));
   std::string expected_json =
-      R"({"coefficients":{"coefficients":["0x1","0x2","0x3","0x4","0x5"]}})";
+      R"({"coefficients":{"coefficients":[1,2,3,4,5]}})";
 
   Poly poly;
   std::string error;
diff --git a/tachyon/math/polynomials/univariate/univariate_evaluations_unittest.cc b/tachyon/math/polynomials/univariate/univariate_evaluations_unittest.cc
index 3c6214478f..2e8a5d12dc 100644
--- a/tachyon/math/polynomials/univariate/univariate_evaluations_unittest.cc
+++ b/tachyon/math/polynomials/univariate/univariate_evaluations_unittest.cc
@@ -285,8 +285,7 @@ TEST_F(UnivariateEvaluationsTest, Hash) {
 
 TEST_F(UnivariateEvaluationsTest, JsonValueConverter) {
   Poly expected_poly({GF7(1), GF7(2), GF7(3), GF7(4), GF7(5)});
-  std::string expected_json =
-      R"({"evaluations":["0x1","0x2","0x3","0x4","0x5"]})";
+  std::string expected_json = R"({"evaluations":[1,2,3,4,5]})";
 
   Poly poly;
   std::string error;
diff --git a/tachyon/math/polynomials/univariate/univariate_sparse_polynomial_unittest.cc b/tachyon/math/polynomials/univariate/univariate_sparse_polynomial_unittest.cc
index 9e9dbc2ef0..fe37f5c138 100644
--- a/tachyon/math/polynomials/univariate/univariate_sparse_polynomial_unittest.cc
+++ b/tachyon/math/polynomials/univariate/univariate_sparse_polynomial_unittest.cc
@@ -451,7 +451,7 @@ TEST_F(UnivariateSparsePolynomialTest, Hash) {
 TEST_F(UnivariateSparsePolynomialTest, JsonValueConverter) {
   Poly expected_poly(Coeffs({{0, GF7(1)}, {1, GF7(2)}, {4, GF7(3)}}));
   std::string expected_json =
-      R"({"coefficients":{"terms":[{"degree":0,"coefficient":"0x1"},{"degree":1,"coefficient":"0x2"},{"degree":4,"coefficient":"0x3"}]}})";
+      R"({"coefficients":{"terms":[{"degree":0,"coefficient":1},{"degree":1,"coefficient":2},{"degree":4,"coefficient":3}]}})";
 
   Poly poly;
   std::string error;