shared_ptr using gcc compiler - c++

Question

I am trying to use shared_ptr in c++. I am using MinGw gcc compiler.
My g++ version is 4.8.1.
When I try to use std::shared_ptr, it says it does not name a type.
Is this because it is part of c++ 11, and that is not supported in the compiled I am using?
Or do I need to set a flag to use c++ 11 features?
EDIT: I tried adding the flag to enable c++ to my makefile, and it still gives an error.
My header where shared_ptr is used is as follows
#pragma once
#include <vector>
#include <memory>
namespace WavFileTools
{
class WavFile;
}
class WavFileTools::WavFile
{
public:
typedef std::vector<unsigned char> PCMData8_t;
typedef std::vector<unsigned short int> PCMData16_t;
struct WavFileHeader {
int num_channels;
int sample_rate;
int bits_per_sample;
};
static std::shared_ptr<WavFile> LoadWavFromFile(std::string filename);
private:
WavFile(void);
private:
WavFileHeader m_header;
PCMData16_t m_data16;
PCMData8_t m_data8;
};
And the makefile...
CC := g++
CFLAGS := -g -O2 -std=c++0x
BIN_DIR := bin
BUILD_DIR := build
SRC_DIR := src
MAIN := WavFileTool
TARGET := wavfiletool.exe
SOURCES := $(wildcard src/*.cpp)
OBJECTS := $(SOURCES:$(SRC_DIR)/%.cpp=$(BUILD_DIR)/%.o)
$(BIN_DIR)/$(TARGET): CREATE_DIRS $(BUILD_DIR)/$(MAIN).o $(OBJECTS)
$(CC) $(OBJECTS) $(CFLAGS) -o $#
$(BUILD_DIR)/$(MAIN).o: $(SRC_DIR)/WavFileTool.cpp
$(CC) $(CFLAGS) -c -o $# $<
$(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp $(SRC_DIR)/%.h
$(CC) $(CC_FLAGS) -c -o $# $<
CREATE_DIRS:
if not exist $(BIN_DIR) mkdir $(BIN_DIR)
if not exist $(BUILD_DIR) mkdir $(BUILD_DIR)
CLEAN:
if exist $(BIN_DIR) rmdir /Q /S $(BIN_DIR) # /S allows deleting non-empty folder, and /Q prevents confirmation required
if exist $(BUILD_DIR) rmdir /Q /S $(BUILD_DIR)
and the error
In file included from src/WavFile.cpp:1:0:
src/WavFile.h:26:10: error: 'shared_ptr' in namespace 'std' does not name a type
static std::shared_ptr<WavFile> LoadWavFromFile(std::string filename);