diff --git a/src/cdrom.emscripten.c b/src/cdrom.emscripten.c
index 2f274c4..1521594 100644
--- a/src/cdrom.emscripten.c
+++ b/src/cdrom.emscripten.c
@@ -29,8 +29,8 @@ static int frame_of_getpos = -1;
 
 static int  cdrom_init(char *);
 static int  cdrom_exit();
-static int  cdrom_start(int, boolean);
-static int  cdrom_stop();
+extern int  cdrom_start(int, boolean);
+extern int  cdrom_stop();
 static int  cdrom_getPlayingInfo(cd_time *);
 
 #define cdrom cdrom_emscripten
@@ -53,15 +53,15 @@ int cdrom_exit() {
 	return OK;
 }
 
-int cdrom_start(int trk, boolean loop) {
-	EM_ASM_ARGS({ xsystem35.cdPlayer.play($0, $1); }, trk, loop);
-	return OK;
-}
+EM_JS(int, cdrom_start, (int trk, boolean loop), {
+	xsystem35.cdPlayer.play(trk, loop);
+	return xsystem35.Status.OK;
+});
 
-int cdrom_stop() {
-	EM_ASM( xsystem35.cdPlayer.stop(); );
-	return OK;
-}
+EM_JS(int, cdrom_stop, (), {
+	xsystem35.cdPlayer.stop();
+	return xsystem35.Status.OK;
+});
 
 int cdrom_getPlayingInfo(cd_time *info) {
 	if (nact->frame_count == frame_of_getpos)
diff --git a/src/midi.emscripten.c b/src/midi.emscripten.c
index 251a78d..94665e1 100644
--- a/src/midi.emscripten.c
+++ b/src/midi.emscripten.c
@@ -28,15 +28,15 @@ static int midi_initilize(char *pname, int subdev);
 static int midi_exit();
 static int midi_start(int no, int loop, char *data, int datalen);
 static int midi_stop();
-static int midi_pause(void);
-static int midi_unpause(void);
+extern int midi_pause(void);
+extern int midi_unpause(void);
 static int midi_get_playing_info(midiplaystate *st);
 static int midi_getflag(int mode, int index);
 static int midi_setflag(int mode, int index, int val);
-static int midi_setvol(int vol);
-static int midi_getvol();
-static int midi_fadestart(int time, int volume, int stop);
-static boolean midi_fading();
+extern int midi_setvol(int vol);
+extern int midi_getvol();
+extern int midi_fadestart(int time, int volume, int stop);
+extern boolean midi_fading();
 
 #define midi midi_emscripten
 mididevice_t midi = {
@@ -83,15 +83,15 @@ static int midi_stop() {
 	return OK;
 }
 
-static int midi_pause(void) {
-	EM_ASM( xsystem35.midiPlayer.pause(); );
-	return OK;
-}
+EM_JS(int, midi_pause, (void), {
+	xsystem35.midiPlayer.pause();
+	return xsystem35.Status.OK;
+});
 
-static int midi_unpause(void) {
-	EM_ASM( xsystem35.midiPlayer.resume(); );
-	return OK;
-}
+EM_JS(int, midi_unpause, (void), {
+	xsystem35.midiPlayer.resume();
+	return xsystem35.Status.OK;
+});
 
 static int midi_get_playing_info(midiplaystate *st) {
 	if (midino != 0) {
@@ -117,20 +117,19 @@ static int midi_setflag(int mode, int index, int val) {
 	return NG;
 }
 
-static int midi_setvol(int vol) {
-	EM_ASM_ARGS({ xsystem35.midiPlayer.setVolume($0); }, vol);
-	return OK;
-}
+EM_JS(int, midi_setvol, (int vol), {
+	xsystem35.midiPlayer.setVolume(vol);
+	return xsystem35.Status.OK;
+});
 
-static int midi_getvol() {
-	return EM_ASM_INT_V( return xsystem35.midiPlayer.getVolume(); );
-}
+EM_JS(int, midi_getvol,(), {
+	return xsystem35.midiPlayer.getVolume();
+});
 
-static int midi_fadestart(int time, int volume, int stop) {
-	return EM_ASM_ARGS({ xsystem35.midiPlayer.fadeStart($0, $1, $2); },
-					   time, volume, stop);
-}
+EM_JS(int, midi_fadestart, (int time, int volume, int stop), {
+	return xsystem35.midiPlayer.fadeStart(time, volume, stop);
+});
 
-static boolean midi_fading() {
-	return EM_ASM_INT_V( return xsystem35.midiPlayer.isFading(); );
-}
+EM_JS(boolean, midi_fading, (), {
+	return xsystem35.midiPlayer.isFading();
+});
diff --git a/src/savedata.c b/src/savedata.c
index 5711711..f9293ea 100644
--- a/src/savedata.c
+++ b/src/savedata.c
@@ -55,11 +55,13 @@ static int   loadSysVar(char *buf);
 static void* loadGameData(int no, int *status, int *size);
 static int   saveGameData(int no, char *buf, int size);
 
-static void scheduleSync() {
 #ifdef __EMSCRIPTEN__
-	EM_ASM( xsystem35.shell.syncfs(); );
+EM_JS(void, scheduleSync, (), {
+	xsystem35.shell.syncfs();
+});
+#else
+#define scheduleSync()
 #endif
-}
 
 /* savefile がある directory を登録 */
 void save_set_path(char *path) {
diff --git a/src/sdl_video.c b/src/sdl_video.c
index 9d896e6..9776f0e 100644
--- a/src/sdl_video.c
+++ b/src/sdl_video.c
@@ -89,13 +89,15 @@ void sdl_Remove(void) {
 }
 
 /* name is UTF-8 */
-void sdl_setWindowTitle(char *name) {
 #ifdef __EMSCRIPTEN__
-	EM_ASM_ARGS({ xsystem35.shell.setWindowTitle(UTF8ToString($0)); }, name);
+EM_JS(void, sdl_setWindowTitle, (char *name), {
+	xsystem35.shell.setWindowTitle(UTF8ToString(name));
+});
 #else
+void sdl_setWindowTitle(char *name) {
 	SDL_SetWindowTitle(sdl_window, name);
-#endif
 }
+#endif
 
 /* Visual に応じて Window を生成する */
 static void window_init(void) {