diff --git a/fmt/format.h b/fmt/format.h
index f4ca4c95..123dd207 100644
--- a/fmt/format.h
+++ b/fmt/format.h
@@ -277,14 +277,6 @@ typedef __int64          intmax_t;
      (FMT_GCC_VERSION >= 303 && FMT_HAS_GXX_CXX11))
 #endif
 
-// Checks if decltype v1.1 is supported
-// http://en.cppreference.com/w/cpp/compiler_support
-#define FMT_HAS_DECLTYPE_INCOMPLETE_RETURN_TYPES \
-    (FMT_HAS_FEATURE(cxx_decltype_incomplete_return_types) || \
-    (FMT_GCC_VERSION >= 407 && FMT_HAS_GXX_CXX11) || \
-    FMT_MSC_VER >= 1900 || \
-    FMT_ICC_VERSION >= 1200)
-
 #ifdef FMT_HEADER_ONLY
 // If header only do not use extern templates.
 # undef FMT_USE_EXTERN_TEMPLATES
diff --git a/fmt/ostream.h b/fmt/ostream.h
index 06b6ab56..84a02d17 100644
--- a/fmt/ostream.h
+++ b/fmt/ostream.h
@@ -68,20 +68,6 @@ struct ConvertToIntImpl<T, true> {
 
 // Write the content of w to os.
 FMT_API void write(std::ostream &os, Writer &w);
-
-#if FMT_HAS_DECLTYPE_INCOMPLETE_RETURN_TYPES
-template<typename T>
-class is_streamable {
-  template<typename U>
-  static auto test(int) -> decltype(std::declval<std::ostream &>() << std::declval<U>(), std::true_type());
-
-  template<typename>
-  static auto test(...) -> std::false_type;
-
-public:
-  static constexpr bool value = decltype(test<T>(0))::value;
-};
-#endif
 }  // namespace internal
 
 // Formats a value.
@@ -110,26 +96,6 @@ void format_arg(BasicFormatter<Char, ArgFormatter_> &f,
  */
 FMT_API void print(std::ostream &os, CStringRef format_str, ArgList args);
 FMT_VARIADIC(void, print, std::ostream &, CStringRef)
-
-#if __cplusplus >= 201103L
-template<typename T, typename Char>
-typename std::enable_if<
- !std::is_same<
-   typename std::remove_cv<typename std::decay<T>::type>::type,
-   char *
- >::value,
- BasicWriter<Char>&
->::type
-operator<<(BasicWriter<Char> &writer, const T &value) {
-  FMT_STATIC_ASSERT(internal::is_streamable<T>::value, "T must be Streamable");
-
-  internal::FormatBuf<Char> format_buf(writer.buffer());
-  std::basic_ostream<Char> output(&format_buf);
-  output << value;
-
-  return writer;
-}
-#endif
 }  // namespace fmt
 
 #ifdef FMT_HEADER_ONLY
diff --git a/test/ostream-test.cc b/test/ostream-test.cc
index 0e84f527..4081b43f 100644
--- a/test/ostream-test.cc
+++ b/test/ostream-test.cc
@@ -111,14 +111,6 @@ std::ostream &operator<<(std::ostream &os, EmptyTest) {
   return os << "";
 }
 
-#if __cplusplus >= 201103L
-struct UserDefinedTest { int i = 42; };
-
-std::ostream &operator<<(std::ostream &os, const UserDefinedTest &u) {
-  return os << u.i;
-}
-#endif
-
 TEST(OStreamTest, EmptyCustomOutput) {
   EXPECT_EQ("", fmt::format("{}", EmptyTest()));
 }
@@ -137,17 +129,6 @@ TEST(OStreamTest, WriteToOStream) {
   EXPECT_EQ("foo", os.str());
 }
 
-#if __cplusplus >= 201103L
-TEST(OStreamTest, WriteUserDefinedTypeToOStream) {
-  std::ostringstream os;
-  fmt::MemoryWriter w;
-  UserDefinedTest u;
-  w << "The answer is " << u;
-  fmt::internal::write(os, w);
-  EXPECT_EQ("The answer is 42", os.str());
-}
-#endif
-
 TEST(OStreamTest, WriteToOStreamMaxSize) {
   std::size_t max_size = std::numeric_limits<std::size_t>::max();
   std::streamsize max_streamsize = std::numeric_limits<std::streamsize>::max();
@@ -191,26 +172,3 @@ TEST(OStreamTest, WriteToOStreamMaxSize) {
   } while (size != 0);
   fmt::internal::write(os, w);
 }
-
-#if __cplusplus >= 201103L
-struct Xs {
-  const size_t size;
-  const std::string s;
-  Xs() : size(200), s(size, 'x') {}
-};
-
-inline std::ostream& operator<<(std::ostream& os, Xs const& xs) {
-  return os << xs.s;
-}
-
-TEST(OStreamTest, FormatBuf1) {
-  Xs xs;
-  fmt::MemoryWriter w;
-  int n = fmt::internal::INLINE_BUFFER_SIZE / xs.size + 1;
-  for (int i = 0; i < n; ++i)
-    w << xs;
-  EXPECT_EQ(w.size(), size_t(n * xs.size));
-  w << xs;
-  EXPECT_EQ(w.size(), size_t((n + 1) * xs.size));
-}
-#endif