diff --git a/aom_dsp/avg.c b/aom_dsp/avg.c
index 7043050..e6eab47 100644
--- a/aom_dsp/avg.c
+++ b/aom_dsp/avg.c
@@ -87,7 +87,7 @@
   int i, j;
   const uint16_t *s = CONVERT_TO_SHORTPTR(s8);
   const uint16_t *d = CONVERT_TO_SHORTPTR(d8);
-  *min = 255;
+  *min = 65535;
   *max = 0;
   for (i = 0; i < 8; ++i, s += p, d += dp) {
     for (j = 0; j < 8; ++j) {
diff --git a/test/minmax_test.cc b/test/minmax_test.cc
new file mode 100644
index 0000000..0a148d2
--- /dev/null
+++ b/test/minmax_test.cc
@@ -0,0 +1,235 @@
+/*
+ *  Copyright (c) 2023 The WebM project authors. All Rights Reserved.
+ *  Copyright (c) 2023, Alliance for Open Media. All Rights Reserved.
+ *
+ *  This source code is subject to the terms of the BSD 2 Clause License and
+ *  the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ *  was not distributed with this source code in the LICENSE file, you can
+ *  obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ *  Media Patent License 1.0 was not distributed with this source code in the
+ *  PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "third_party/googletest/src/googletest/include/gtest/gtest.h"
+
+#include "config/aom_config.h"
+#include "config/aom_dsp_rtcd.h"
+#include "aom_ports/mem.h"
+#include "test/acm_random.h"
+#include "test/register_state_check.h"
+#include "test/util.h"
+
+namespace {
+
+using ::libaom_test::ACMRandom;
+
+typedef void (*MinMaxFunc)(const uint8_t *a, int a_stride, const uint8_t *b,
+                           int b_stride, int *min, int *max);
+
+class MinMaxTest : public ::testing::TestWithParam<MinMaxFunc> {
+ public:
+  virtual void SetUp() {
+    mm_func_ = GetParam();
+    rnd_.Reset(ACMRandom::DeterministicSeed());
+  }
+
+ protected:
+  MinMaxFunc mm_func_;
+  ACMRandom rnd_;
+};
+
+void reference_minmax(const uint8_t *a, int a_stride, const uint8_t *b,
+                      int b_stride, int *min_ret, int *max_ret) {
+  int min = 255;
+  int max = 0;
+  for (int i = 0; i < 8; i++) {
+    for (int j = 0; j < 8; j++) {
+      const int diff = abs(a[i * a_stride + j] - b[i * b_stride + j]);
+      if (min > diff) min = diff;
+      if (max < diff) max = diff;
+    }
+  }
+
+  *min_ret = min;
+  *max_ret = max;
+}
+
+TEST_P(MinMaxTest, MinValue) {
+  for (int i = 0; i < 64; i++) {
+    uint8_t a[64], b[64];
+    memset(a, 0, sizeof(a));
+    memset(b, 255, sizeof(b));
+    b[i] = i;  // Set a minimum difference of i.
+
+    int min, max;
+    API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+    EXPECT_EQ(255, max);
+    EXPECT_EQ(i, min);
+  }
+}
+
+TEST_P(MinMaxTest, MaxValue) {
+  for (int i = 0; i < 64; i++) {
+    uint8_t a[64], b[64];
+    memset(a, 0, sizeof(a));
+    memset(b, 0, sizeof(b));
+    b[i] = i;  // Set a maximum difference of i.
+
+    int min, max;
+    API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+    EXPECT_EQ(i, max);
+    EXPECT_EQ(0, min);
+  }
+}
+
+TEST_P(MinMaxTest, CompareReference) {
+  uint8_t a[64], b[64];
+  for (int j = 0; j < 64; j++) {
+    a[j] = rnd_.Rand8();
+    b[j] = rnd_.Rand8();
+  }
+
+  int min_ref, max_ref, min, max;
+  reference_minmax(a, 8, b, 8, &min_ref, &max_ref);
+  API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+  EXPECT_EQ(max_ref, max);
+  EXPECT_EQ(min_ref, min);
+}
+
+TEST_P(MinMaxTest, CompareReferenceAndVaryStride) {
+  uint8_t a[8 * 64], b[8 * 64];
+  for (int i = 0; i < 8 * 64; i++) {
+    a[i] = rnd_.Rand8();
+    b[i] = rnd_.Rand8();
+  }
+  for (int a_stride = 8; a_stride <= 64; a_stride += 8) {
+    for (int b_stride = 8; b_stride <= 64; b_stride += 8) {
+      int min_ref, max_ref, min, max;
+      reference_minmax(a, a_stride, b, b_stride, &min_ref, &max_ref);
+      API_REGISTER_STATE_CHECK(mm_func_(a, a_stride, b, b_stride, &min, &max));
+      EXPECT_EQ(max_ref, max)
+          << "when a_stride = " << a_stride << " and b_stride = " << b_stride;
+      EXPECT_EQ(min_ref, min)
+          << "when a_stride = " << a_stride << " and b_stride = " << b_stride;
+    }
+  }
+}
+
+#if CONFIG_AV1_HIGHBITDEPTH
+
+using HBDMinMaxTest = MinMaxTest;
+
+void highbd_reference_minmax(const uint8_t *a, int a_stride, const uint8_t *b,
+                             int b_stride, int *min_ret, int *max_ret) {
+  int min = 65535;
+  int max = 0;
+  const uint16_t *a_ptr = CONVERT_TO_SHORTPTR(a);
+  const uint16_t *b_ptr = CONVERT_TO_SHORTPTR(b);
+  for (int i = 0; i < 8; i++) {
+    for (int j = 0; j < 8; j++) {
+      const int diff = abs(a_ptr[i * a_stride + j] - b_ptr[i * b_stride + j]);
+      if (min > diff) min = diff;
+      if (max < diff) max = diff;
+    }
+  }
+
+  *min_ret = min;
+  *max_ret = max;
+}
+
+TEST_P(HBDMinMaxTest, MinValue) {
+  uint8_t *a = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  uint8_t *b = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  for (int i = 0; i < 64; i++) {
+    aom_memset16(CONVERT_TO_SHORTPTR(a), 0, 64);
+    aom_memset16(CONVERT_TO_SHORTPTR(b), 65535, 64);
+    CONVERT_TO_SHORTPTR(b)[i] = i;  // Set a minimum difference of i.
+
+    int min, max;
+    API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+    EXPECT_EQ(65535, max);
+    EXPECT_EQ(i, min);
+  }
+  aom_free(CONVERT_TO_SHORTPTR(a));
+  aom_free(CONVERT_TO_SHORTPTR(b));
+}
+
+TEST_P(HBDMinMaxTest, MaxValue) {
+  uint8_t *a = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  uint8_t *b = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  for (int i = 0; i < 64; i++) {
+    aom_memset16(CONVERT_TO_SHORTPTR(a), 0, 64);
+    aom_memset16(CONVERT_TO_SHORTPTR(b), 0, 64);
+    CONVERT_TO_SHORTPTR(b)[i] = i;  // Set a minimum difference of i.
+
+    int min, max;
+    API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+    EXPECT_EQ(i, max);
+    EXPECT_EQ(0, min);
+  }
+  aom_free(CONVERT_TO_SHORTPTR(a));
+  aom_free(CONVERT_TO_SHORTPTR(b));
+}
+
+TEST_P(HBDMinMaxTest, CompareReference) {
+  uint8_t *a = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  uint8_t *b = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc(64 * sizeof(uint16_t))));
+  for (int j = 0; j < 64; j++) {
+    CONVERT_TO_SHORTPTR(a)[j] = rnd_.Rand16();
+    CONVERT_TO_SHORTPTR(b)[j] = rnd_.Rand16();
+  }
+
+  int min_ref, max_ref, min, max;
+  highbd_reference_minmax(a, 8, b, 8, &min_ref, &max_ref);
+  API_REGISTER_STATE_CHECK(mm_func_(a, 8, b, 8, &min, &max));
+  aom_free(CONVERT_TO_SHORTPTR(a));
+  aom_free(CONVERT_TO_SHORTPTR(b));
+  EXPECT_EQ(max_ref, max);
+  EXPECT_EQ(min_ref, min);
+}
+
+TEST_P(HBDMinMaxTest, CompareReferenceAndVaryStride) {
+  uint8_t *a = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc((8 * 64) * sizeof(uint16_t))));
+  uint8_t *b = CONVERT_TO_BYTEPTR(
+      reinterpret_cast<uint16_t *>(aom_malloc((8 * 64) * sizeof(uint16_t))));
+  for (int i = 0; i < 8 * 64; i++) {
+    CONVERT_TO_SHORTPTR(a)[i] = rnd_.Rand16();
+    CONVERT_TO_SHORTPTR(b)[i] = rnd_.Rand16();
+  }
+  for (int a_stride = 8; a_stride <= 64; a_stride += 8) {
+    for (int b_stride = 8; b_stride <= 64; b_stride += 8) {
+      int min_ref, max_ref, min, max;
+      highbd_reference_minmax(a, a_stride, b, b_stride, &min_ref, &max_ref);
+      API_REGISTER_STATE_CHECK(mm_func_(a, a_stride, b, b_stride, &min, &max));
+      EXPECT_EQ(max_ref, max)
+          << "when a_stride = " << a_stride << " and b_stride = " << b_stride;
+      EXPECT_EQ(min_ref, min)
+          << "when a_stride = " << a_stride << " and b_stride = " << b_stride;
+    }
+  }
+  aom_free(CONVERT_TO_SHORTPTR(a));
+  aom_free(CONVERT_TO_SHORTPTR(b));
+}
+#endif  // CONFIG_AV1_HIGHBITDEPTH
+
+INSTANTIATE_TEST_SUITE_P(C, MinMaxTest, ::testing::Values(&aom_minmax_8x8_c));
+#if CONFIG_AV1_HIGHBITDEPTH
+INSTANTIATE_TEST_SUITE_P(C, HBDMinMaxTest,
+                         ::testing::Values(&aom_highbd_minmax_8x8_c));
+#endif
+
+#if HAVE_SSE2
+INSTANTIATE_TEST_SUITE_P(SSE2, MinMaxTest,
+                         ::testing::Values(&aom_minmax_8x8_sse2));
+#endif
+}  // namespace
diff --git a/test/test.cmake b/test/test.cmake
index 95fb1e0..5f7e9a4 100644
--- a/test/test.cmake
+++ b/test/test.cmake
@@ -203,6 +203,7 @@
               "${AOM_ROOT}/test/horver_correlation_test.cc"
               "${AOM_ROOT}/test/masked_sad_test.cc"
               "${AOM_ROOT}/test/masked_variance_test.cc"
+              "${AOM_ROOT}/test/minmax_test.cc"
               "${AOM_ROOT}/test/motion_vector_test.cc"
               "${AOM_ROOT}/test/mv_cost_test.cc"
               "${AOM_ROOT}/test/noise_model_test.cc"