diff --git a/src/input.c b/src/input.c
index e10db38..8cfa726 100644
--- a/src/input.c
+++ b/src/input.c
@@ -44,17 +44,14 @@ void enable_msgSkip(boolean enable) {
 	if (enable == msgskip_enabled)
 		return;
 	msgskip_enabled = enable;
-#ifdef _WIN32
-	win_menu_enableMsgSkip(enable);
-#endif
+	menu_setSkipState(msgskip_enabled, skipToNextSel);
 }
 
 void set_skipMode(boolean skip) {
-#ifdef _WIN32
-	if (skipToNextSel != skip)
-		win_menu_skipModeChanged(skip);
-#endif
+	if (skipToNextSel == skip)
+		return;
 	skipToNextSel = skip;
+	menu_setSkipState(msgskip_enabled, skipToNextSel);
 }
 
 boolean get_skipMode() {
diff --git a/src/menu.c b/src/menu.c
index 0469276..f2341a6 100644
--- a/src/menu.c
+++ b/src/menu.c
@@ -176,3 +176,6 @@ void menu_gtkmainiteration() {
 		menu_callback();
 	}
 }
+
+void menu_setSkipState(boolean enabled, boolean activated) {
+}
diff --git a/src/menu.h b/src/menu.h
index cfc933c..d842602 100644
--- a/src/menu.h
+++ b/src/menu.h
@@ -54,13 +54,12 @@ extern void menu_msgbox_open(char *);
 extern void menu_widgetinit(void);
 extern void menu_init();
 extern void menu_gtkmainiteration();
+extern void menu_setSkipState(boolean enabled, boolean activated);
 
 #ifdef _WIN32
 struct SDL_SysWMmsg;
 extern void win_menu_init(void);
 extern void win_menu_onsyswmevent(struct SDL_SysWMmsg* msg);
-extern void win_menu_skipModeChanged(boolean skip);
-extern void win_menu_enableMsgSkip(boolean enabled);
 #endif
 
 #endif /* !__MENULL */
diff --git a/src/menu_android.c b/src/menu_android.c
index 8b4bca2..3db6094 100644
--- a/src/menu_android.c
+++ b/src/menu_android.c
@@ -111,3 +111,6 @@ void menu_init(void) {
 void menu_gtkmainiteration() {
 	return;
 }
+
+void menu_setSkipState(boolean enabled, boolean activated) {
+}
diff --git a/src/menu_emscripten.c b/src/menu_emscripten.c
index 1de3ff2..ff60456 100644
--- a/src/menu_emscripten.c
+++ b/src/menu_emscripten.c
@@ -25,6 +25,7 @@
 
 #include "portab.h"
 #include "menu.h"
+#include "input.h"
 
 void menu_open(void) {
 	return;
@@ -74,3 +75,12 @@ void menu_init(void) {
 void menu_gtkmainiteration() {
 	return;
 }
+
+EM_JS(void, menu_setSkipState, (boolean enabled, boolean activated), {
+	xsystem35.shell.setSkipButtonState(enabled, activated);
+});
+
+EMSCRIPTEN_KEEPALIVE
+void msgskip_activate(int enable) {
+	set_skipMode(enable);
+}
diff --git a/src/menu_sdl.c b/src/menu_sdl.c
index 8e0bb2d..d758f55 100644
--- a/src/menu_sdl.c
+++ b/src/menu_sdl.c
@@ -96,3 +96,8 @@ void menu_init(void) {
 void menu_gtkmainiteration() {
 	return;
 }
+
+#ifndef _WIN32
+void menu_setSkipState(boolean enabled, boolean activated) {
+}
+#endif
diff --git a/src/msgskip.c b/src/msgskip.c
index 57344be..35a591b 100644
--- a/src/msgskip.c
+++ b/src/msgskip.c
@@ -23,6 +23,10 @@
 #include "mmap.h"
 #include "input.h"
 #include "scenario.h"
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#include <sys/mman.h>
+#endif
 
 // These parameters are chosen so that the false positive rate is less than 0.5%
 // in Kichikuou Rance (122,915 distinct messages).
@@ -37,6 +41,7 @@ typedef struct {
 static struct {
 	mmap_t *map;
 	MsgSkipData *data;
+	boolean dirty;
 } msgskip;
 
 // Knuth's multiplicative hash.
@@ -53,11 +58,16 @@ void msgskip_init(const char *msgskip_file) {
 		return;
 	msgskip.map = m;
 	msgskip.data = m->addr;
+	msgskip.dirty = false;
 
 	if (msgskip.data->size != BLOOM_FILTER_SIZE) {
 		msgskip.data->size = BLOOM_FILTER_SIZE;
 		memset(msgskip.data->bloom, 0, length - 4);
 	}
+
+#ifdef __EMSCRIPTEN__
+	EM_ASM({ setInterval(() => _msgskip_syncFile(), 5000); });
+#endif
 }
 
 void msgskip_onMessage(void) {
@@ -73,9 +83,23 @@ void msgskip_onMessage(void) {
 		msgskip.data->bloom[h >> 3] |= bit;
 	}
 	if (unseen) {
+		msgskip.dirty = true;
 		set_skipMode(FALSE);
 		enable_msgSkip(FALSE);
 	} else {
 		enable_msgSkip(TRUE);
 	}
 }
+
+#ifdef __EMSCRIPTEN__
+
+EMSCRIPTEN_KEEPALIVE
+void msgskip_syncFile() {
+	if (!msgskip.dirty)
+		return;
+	msync(msgskip.map->addr, msgskip.map->length, MS_ASYNC);
+	EM_ASM( xsystem35.shell.syncfs(); );
+	msgskip.dirty = false;
+}
+
+#endif // __EMSCRIPTEN__
diff --git a/src/win/menubar.c b/src/win/menubar.c
index c639cc3..296d514 100644
--- a/src/win/menubar.c
+++ b/src/win/menubar.c
@@ -64,9 +64,12 @@ void win_menu_onsyswmevent(SDL_SysWMmsg* msg) {
 	}
 }
 
-void win_menu_skipModeChanged(boolean skip) {
+void menu_setSkipState(boolean enabled, boolean activated) {
 	HWND hwnd = get_hwnd(sdl_window);
 	HMENU hmenu = GetMenu(hwnd);
+
+	EnableMenuItem(hmenu, ID_MSGSKIP, enabled ? MF_ENABLED : MF_GRAYED);
+
 	wchar_t buf[20];
 	MENUITEMINFOW menuitem = {
 		.cbSize = sizeof(MENUITEMINFOW),
@@ -74,19 +77,13 @@ void win_menu_skipModeChanged(boolean skip) {
 		.dwTypeData = buf,
 		.cch = sizeof(buf) / sizeof(wchar_t),
 	};
-	if (!GetMenuItemInfoW(hmenu, ID_MSGSKIP, false, &menuitem))
-		return;
-	wchar_t *p = wcsrchr(buf, L'[');
-	if (!p)
-		return;
-	wcscpy(p, skip ? L"[on]" : L"[off]");
-	SetMenuItemInfoW(hmenu, ID_MSGSKIP, false, &menuitem);
-	DrawMenuBar(hwnd);
-}
+	if (GetMenuItemInfoW(hmenu, ID_MSGSKIP, false, &menuitem)) {
+		wchar_t *p = wcsrchr(buf, L'[');
+		if (p) {
+			wcscpy(p, activated ? L"[on]" : L"[off]");
+			SetMenuItemInfoW(hmenu, ID_MSGSKIP, false, &menuitem);
+		}
+	}
 
-void win_menu_enableMsgSkip(boolean enabled) {
-	HWND hwnd = get_hwnd(sdl_window);
-	HMENU hmenu = GetMenu(hwnd);
-	EnableMenuItem(hmenu, ID_MSGSKIP, enabled ? MF_ENABLED : MF_GRAYED);
 	DrawMenuBar(hwnd);
 }