diff --git a/tests/wchar_test.cpp b/tests/wchar_test.cpp
new file mode 100644
index 0000000..20566f2
--- /dev/null
+++ b/tests/wchar_test.cpp
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * 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 <gtest/gtest.h>
+
+#include <limits.h>
+#include <wchar.h>
+
+TEST(wchar, sizeof_wchar_t) {
+  EXPECT_EQ(4U, sizeof(wchar_t));
+  EXPECT_EQ(4U, sizeof(wint_t));
+}
+
+TEST(wchar, mbrlen) {
+  char bytes[] = { 'h', 'e', 'l', 'l', 'o', '\0' };
+  EXPECT_EQ(0U, mbrlen(&bytes[0], 0, NULL));
+  EXPECT_EQ(1U, mbrlen(&bytes[0], 1, NULL));
+
+  EXPECT_EQ(1U, mbrlen(&bytes[4], 1, NULL));
+  EXPECT_EQ(0U, mbrlen(&bytes[5], 1, NULL));
+}
+
+TEST(wchar, wctomb_wcrtomb) {
+  // wctomb and wcrtomb behave differently when s == NULL.
+  EXPECT_EQ(0, wctomb(NULL, L'h'));
+  EXPECT_EQ(0, wctomb(NULL, L'\0'));
+  EXPECT_EQ(1U, wcrtomb(NULL, L'\0', NULL));
+  EXPECT_EQ(1U, wcrtomb(NULL, L'h', NULL));
+
+  char bytes[MB_LEN_MAX];
+
+  // wctomb and wcrtomb behave similarly for the null wide character.
+  EXPECT_EQ(1, wctomb(bytes, L'\0'));
+  EXPECT_EQ(1U, wcrtomb(bytes, L'\0', NULL));
+
+  // ...and for regular characters.
+  bytes[0] = 'x';
+  EXPECT_EQ(1, wctomb(bytes, L'h'));
+  EXPECT_EQ('h', bytes[0]);
+
+  bytes[0] = 'x';
+  EXPECT_EQ(1U, wcrtomb(bytes, L'h', NULL));
+  EXPECT_EQ('h', bytes[0]);
+}