diff --git a/cpp/include/raft/linalg/mean_squared_error.cuh b/cpp/include/raft/linalg/mean_squared_error.cuh
index 298f32339c..a3360ae35a 100644
--- a/cpp/include/raft/linalg/mean_squared_error.cuh
+++ b/cpp/include/raft/linalg/mean_squared_error.cuh
@@ -35,9 +35,9 @@ namespace linalg {
  * @param weight weight to apply to every term in the mean squared error calculation
  * @param stream cuda-stream where to launch this kernel
  */
-template <typename in_t, typename out_t, typename idx_t>
+template <typename in_t, typename out_t, typename idx_t = size_t>
 void meanSquaredError(
-  out_t* out, const in_t* A, const in_t* B, size_t len, in_t weight, cudaStream_t stream)
+  out_t* out, const in_t* A, const in_t* B, idx_t len, in_t weight, cudaStream_t stream)
 {
   detail::meanSquaredError(out, A, B, len, weight, stream);
 }
diff --git a/cpp/test/CMakeLists.txt b/cpp/test/CMakeLists.txt
index 0d5af9be5c..8f04537b6b 100644
--- a/cpp/test/CMakeLists.txt
+++ b/cpp/test/CMakeLists.txt
@@ -140,6 +140,7 @@ if(BUILD_TESTS)
             test/linalg/map.cu
             test/linalg/map_then_reduce.cu
             test/linalg/matrix_vector_op.cu
+            test/linalg/mean_squared_error.cu
             test/linalg/multiply.cu
             test/linalg/norm.cu
             test/linalg/power.cu
diff --git a/cpp/test/linalg/mean_squared_error.cu b/cpp/test/linalg/mean_squared_error.cu
new file mode 100644
index 0000000000..795f831417
--- /dev/null
+++ b/cpp/test/linalg/mean_squared_error.cu
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2022, NVIDIA CORPORATION.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <raft/linalg/mean_squared_error.cuh>
+
+#include "../test_utils.h"
+#include <gtest/gtest.h>
+#include <raft/random/rng.cuh>
+#include <raft/util/cuda_utils.cuh>
+#include <rmm/device_scalar.hpp>
+
+namespace raft {
+namespace linalg {
+
+// reference MSE calculation
+template <typename T>
+__global__ void naiveMeanSquaredError(const int n, const T* a, const T* b, T weight, T* out)
+{
+  T err = 0;
+  for (int i = blockIdx.x * blockDim.x + threadIdx.x; i < n; i += blockDim.x * gridDim.x) {
+    T diff = a[i] - b[i];
+    err += weight * diff * diff / n;
+  }
+  atomicAdd(out, err);
+}
+
+template <typename T, typename IndexType = std::uint32_t>
+struct MeanSquaredErrorInputs {
+  T tolerance;
+  IndexType len;
+  T weight;
+  unsigned long long int seed;
+};
+
+template <typename T>
+class MeanSquaredErrorTest : public ::testing::TestWithParam<MeanSquaredErrorInputs<T>> {
+ protected:
+  MeanSquaredErrorInputs<T> params;
+
+  raft::handle_t handle;
+  rmm::device_scalar<T> output;
+  rmm::device_scalar<T> refoutput;
+
+ public:
+  MeanSquaredErrorTest()
+    : testing::TestWithParam<MeanSquaredErrorInputs<T>>(),
+      output(0, handle.get_stream()),
+      refoutput(0, handle.get_stream())
+  {
+    handle.sync_stream();
+  }
+
+ protected:
+  void SetUp() override
+  {
+    params = ::testing::TestWithParam<MeanSquaredErrorInputs<T>>::GetParam();
+
+    cudaStream_t stream = handle.get_stream();
+
+    raft::random::RngState r(params.seed);
+
+    rmm::device_uvector<T> a(params.len, stream);
+    rmm::device_uvector<T> b(params.len, stream);
+    uniform(handle, r, a.data(), params.len, T(-1.0), T(1.0));
+    uniform(handle, r, b.data(), params.len, T(-1.0), T(1.0));
+    handle.sync_stream();
+
+    mean_squared_error<T, std::uint32_t, T>(handle,
+                                            make_device_vector_view<const T>(a.data(), params.len),
+                                            make_device_vector_view<const T>(b.data(), params.len),
+                                            make_device_scalar_view<T>(output.data()),
+                                            params.weight);
+
+    naiveMeanSquaredError<<<256, 256, 0, stream>>>(
+      params.len, a.data(), b.data(), params.weight, refoutput.data());
+    handle.sync_stream();
+  }
+
+  void TearDown() override {}
+};
+
+const std::vector<MeanSquaredErrorInputs<float>> inputsf = {
+  {0.0001f, 1024 * 1024, 1.0, 1234ULL},
+  {0.0001f, 4 * 1024 * 1024, 8.0, 1234ULL},
+  {0.0001f, 16 * 1024 * 1024, 24.0, 1234ULL},
+  {0.0001f, 98689, 1.0, 1234ULL},
+};
+
+const std::vector<MeanSquaredErrorInputs<double>> inputsd = {
+  {0.0001f, 1024 * 1024, 1.0, 1234ULL},
+  {0.0001f, 4 * 1024 * 1024, 8.0, 1234ULL},
+  {0.0001f, 16 * 1024 * 1024, 24.0, 1234ULL},
+  {0.0001f, 98689, 1.0, 1234ULL},
+};
+
+typedef MeanSquaredErrorTest<float> MeanSquaredErrorTestF;
+TEST_P(MeanSquaredErrorTestF, Result)
+{
+  ASSERT_TRUE(raft::devArrMatch(
+    refoutput.data(), output.data(), 1, raft::CompareApprox<float>(params.tolerance)));
+}
+
+typedef MeanSquaredErrorTest<double> MeanSquaredErrorTestD;
+TEST_P(MeanSquaredErrorTestD, Result)
+{
+  ASSERT_TRUE(raft::devArrMatch(
+    refoutput.data(), output.data(), 1, raft::CompareApprox<double>(params.tolerance)));
+}
+
+INSTANTIATE_TEST_SUITE_P(MeanSquaredErrorTests,
+                         MeanSquaredErrorTestF,
+                         ::testing::ValuesIn(inputsf));
+
+INSTANTIATE_TEST_SUITE_P(MeanSquaredErrorTests,
+                         MeanSquaredErrorTestD,
+                         ::testing::ValuesIn(inputsd));
+
+}  // end namespace linalg
+}  // end namespace raft