Detecting the Back key on Android

I’m using this code to try and detect when the user presses the Back button on an Android device:

					case SDL_KEYDOWN:						
						if (event.key.keysym.sym == SDLK_AC_BACK)
							// back key is pressed

Pressing the back button on the emulator fires the SDL_KEYDOWN event, but event.key.keysym.sym is 27, whereas SDLK_AC_BACK seems to be defined as 1073742094

But on an actual device SDLK_AC_BACK seems to work

Not sure what I’m doing wrong?