diff --git a/cppformat/posix.h b/cppformat/posix.h
index 3f02f388..ae8b4724 100644
--- a/cppformat/posix.h
+++ b/cppformat/posix.h
@@ -335,7 +335,10 @@ class File {
 long getpagesize();
 
 #if defined(LC_NUMERIC_MASK) || defined(_MSC_VER)
+# define FMT_LOCALE
+#endif
 
+#ifdef FMT_LOCALE
 // A "C" numeric locale.
 class Locale {
  private:
@@ -362,13 +365,15 @@ class Locale {
   FMT_DISALLOW_COPY_AND_ASSIGN(Locale);
 
  public:
+  typedef locale_t Type;
+
   Locale() : locale_(newlocale(LC_NUMERIC_MASK, "C", NULL)) {
     if (!locale_)
       throw fmt::SystemError(errno, "cannot create locale");
   }
   ~Locale() { freelocale(locale_); }
 
-  locale_t get() const { return locale_; }
+  Type get() const { return locale_; }
 
   // Converts string to floating-point number and advances str past the end
   // of the parsed input.
@@ -379,8 +384,7 @@ class Locale {
     return result;
   }
 };
-
-#endif  // LC_NUMERIC
+#endif  // FMT_LOCALE
 }  // namespace fmt
 
 #if !FMT_USE_RVALUE_REFERENCES
diff --git a/test/posix-mock-test.cc b/test/posix-mock-test.cc
index e1854c03..13ed1220 100644
--- a/test/posix-mock-test.cc
+++ b/test/posix-mock-test.cc
@@ -41,6 +41,7 @@
 # undef ERROR
 #endif
 
+#include "gmock/gmock.h"
 #include "gtest-extra.h"
 #include "util.h"
 
@@ -49,6 +50,9 @@ using fmt::ErrorCode;
 using fmt::File;
 
 using testing::internal::scoped_ptr;
+using testing::_;
+using testing::StrEq;
+using testing::Return;
 
 namespace {
 int open_count;
@@ -449,3 +453,108 @@ TEST(BufferedFileTest, FilenoNoRetry) {
   EXPECT_EQ(2, fileno_count);
   fileno_count = 0;
 }
+
+template <typename Mock>
+struct ScopedMock : testing::StrictMock<Mock> {
+ private:
+  Mock *&global_mock_;
+
+ public:
+  explicit ScopedMock(Mock *&global_mock) : global_mock_(global_mock) {
+    global_mock = this;
+  }
+  ~ScopedMock() { global_mock_ = 0; }
+};
+
+struct TestMock {};
+
+TEST(ScopedMock, Scope) {
+  TestMock *global_mock = 0;
+  {
+    ScopedMock<TestMock> mock(global_mock);
+    EXPECT_EQ(&mock, global_mock);
+    TestMock &copy = mock;
+  }
+  EXPECT_EQ(0, global_mock);
+}
+
+#ifdef FMT_LOCALE
+
+typedef fmt::Locale::Type LocaleType;
+
+struct LocaleMock {
+  MOCK_METHOD3(newlocale, LocaleType (int category_mask, const char *locale,
+                                      LocaleType base));
+  MOCK_METHOD1(freelocale, void (LocaleType locale));
+
+  MOCK_METHOD3(strtod_l, double (const char *nptr, char **endptr,
+                                 LocaleType locale));
+} *locale_mock;
+
+#ifdef _MSC_VER
+_locale_t _create_locale(int category, const char *locale) {
+  return locale_mock->newlocale(category, locale, 0);
+}
+
+void _free_locale(_locale_t locale) {
+  locale_mock->freelocale(locale);
+}
+
+double _strtod_l(const char *nptr, char **endptr, _locale_t locale) {
+  return locale_mock->strtod_l(nptr, endptr, locale);
+}
+#endif
+
+LocaleType newlocale(int category_mask, const char *locale, LocaleType base) {
+  return locale_mock->newlocale(category_mask, locale, base);
+}
+
+#ifdef __APPLE__
+typedef int FreeLocaleResult;
+#else
+typedef void FreeLocaleResult;
+#endif
+
+FreeLocaleResult freelocale(LocaleType locale) {
+  locale_mock->freelocale(locale);
+}
+
+double strtod_l(const char *nptr, char **endptr, LocaleType locale) {
+  return locale_mock->strtod_l(nptr, endptr, locale);
+}
+
+TEST(LocaleTest, LocaleMock) {
+  ScopedMock<LocaleMock> mock(locale_mock);
+  LocaleType locale = reinterpret_cast<LocaleType>(11);
+  EXPECT_CALL(mock, newlocale(222, StrEq("foo"), locale));
+  newlocale(222, "foo", locale);
+}
+
+TEST(LocaleTest, Locale) {
+#ifndef LC_NUMERIC_MASK
+  enum { LC_NUMERIC_MASK = LC_NUMERIC };
+#endif
+  ScopedMock<LocaleMock> mock(locale_mock);
+  LocaleType impl = reinterpret_cast<LocaleType>(42);
+  EXPECT_CALL(mock, newlocale(LC_NUMERIC_MASK, StrEq("C"), 0))
+      .WillOnce(Return(impl));
+  EXPECT_CALL(mock, freelocale(impl));
+  fmt::Locale locale;
+  EXPECT_EQ(impl, locale.get());
+}
+
+TEST(LocaleTest, Strtod) {
+  ScopedMock<LocaleMock> mock(locale_mock);
+  EXPECT_CALL(mock, newlocale(_, _, _))
+      .WillOnce(Return(reinterpret_cast<LocaleType>(42)));
+  EXPECT_CALL(mock, freelocale(_));
+  fmt::Locale locale;
+  const char *str = "4.2";
+  char end = 'x';
+  EXPECT_CALL(mock, strtod_l(str, _, locale.get()))
+      .WillOnce(testing::DoAll(testing::SetArgPointee<1>(&end), Return(777)));
+  EXPECT_EQ(777, locale.strtod(str));
+  EXPECT_EQ(&end, str);
+}
+
+#endif  // FMT_LOCALE
diff --git a/test/posix-test.cc b/test/posix-test.cc
index 03ac43d8..f6e3b99d 100644
--- a/test/posix-test.cc
+++ b/test/posix-test.cc
@@ -388,7 +388,7 @@ TEST(FileTest, FdopenError) {
       f.fdopen("r"), EBADF, "cannot associate stream with file descriptor");
 }
 
-#ifdef LC_NUMERIC_MASK
+#ifdef FMT_LOCALE
 TEST(LocaleTest, Strtod) {
   fmt::Locale locale;
   const char *start = "4.2", *ptr = start;