In-class initialization of std::map

I have this snippet of C++ code that doesn't compile under g++-4.9.1 (I used the command "g++ -c --std=c++11 map.cc")

#include <map>
#include <cstdint>
class A {
  std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>();
};

I get the following error when compiling:

map.cc:5:52: error: expected ‘;’ at end of member declaration
   std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>();
                                                    ^
map.cc:5:52: error: declaration of ‘std::map<unsigned char, unsigned char> A::uint8_t’ [-fpermissive]
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.9/include/stdint.h:9:0,
                 from /usr/include/c++/4.9/cstdint:41,
                 from /usr/include/c++/4.9/bits/char_traits.h:380,
                 from /usr/include/c++/4.9/string:40,
                 from /usr/include/c++/4.9/stdexcept:39,
                 from /usr/include/c++/4.9/array:38,
                 from /usr/include/c++/4.9/tuple:39,
                 from /usr/include/c++/4.9/bits/stl_map.h:63,
                 from /usr/include/c++/4.9/map:61,
                 from map.cc:1:
/usr/include/stdint.h:48:24: error: changes meaning of ‘uint8_t’ from ‘typedef unsigned char uint8_t’ [-fpermissive]
 typedef unsigned char  uint8_t;
                        ^
map.cc:5:59: error: expected unqualified-id before ‘>’ token
   std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>();
                                                           ^
map.cc:5:43: error: wrong number of template arguments (1, should be 4)
   std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>();
                                           ^
In file included from /usr/include/c++/4.9/map:61:0,
                 from map.cc:1:
/usr/include/c++/4.9/bits/stl_map.h:96:11: error: provided for ‘template<class _Key, class _Tp, class _Compare, class _Alloc> class std::map’
     class map
           ^

However, if I replace uint8_t with int, it compiles fine.