diff --git a/libc/test/src/wchar/CMakeLists.txt b/libc/test/src/wchar/CMakeLists.txt
@@ -0,0 +1,21 @@
+add_libc_testsuite(libc_wchar_unittests)
+
+add_libc_unittest(
+  btowc_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    btowc_test.cpp
+  DEPENDS
+    libc.src.wchar.btowc
+)
+
+add_libc_unittest(
+  wctob_test
+  SUITE
+    libc_wchar_unittests
+  SRCS
+    wctob_test.cpp
+  DEPENDS
+    libc.src.wchar.wctob
+)
diff --git a/libc/test/src/wchar/btowc_test.cpp b/libc/test/src/wchar/btowc_test.cpp
@@ -0,0 +1,24 @@
+//===-- Unittests for btowc ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <wchar.h> //for WEOF
+
+#include "src/wchar/btowc.h"
+
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcBtowc, DefaultLocale) {
+  // Loops through all characters, verifying that ascii returns itself and
+  // everything else returns WEOF.
+  for (int c = 0; c < 255; ++c) {
+    if (c < 128)
+      EXPECT_EQ(__llvm_libc::btowc(c), static_cast<wint_t>(c));
+    else
+      EXPECT_EQ(__llvm_libc::btowc(c), WEOF);
+  }
+}
diff --git a/libc/test/src/wchar/wctob_test.cpp b/libc/test/src/wchar/wctob_test.cpp
@@ -0,0 +1,24 @@
+//===-- Unittests for wctob ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <stdio.h> //for EOF
+
+#include "src/wchar/wctob.h"
+
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcWctob, DefaultLocale) {
+  // Loops through a subset of the wide characters, verifying that ascii returns
+  // itself and everything else returns EOF.
+  for (wint_t c = 0; c < 32767; ++c) {
+    if (c < 128)
+      EXPECT_EQ(__llvm_libc::wctob(c), static_cast<int>(c));
+    else
+      EXPECT_EQ(__llvm_libc::wctob(c), EOF);
+  }
+}