diff --git a/in_sdl.c b/in_sdl.c
index a84c781..bab649a 100644
--- a/in_sdl.c
+++ b/in_sdl.c
@@ -19,11 +19,18 @@
 typedef unsigned long keybits_t;
 #define KEYBITS_WORD_BITS (sizeof(keybits_t) * 8)
 
+enum mod_state {
+	MOD_NO,
+	MOD_MAYBE,
+	MOD_YES
+};
+
 struct in_sdl_state {
 	const in_drv_t *drv;
 	SDL_Joystick *joy;
 	int joy_id;
 	int axis_keydown[2];
+	enum mod_state mod_state;
 	keybits_t keystate[SDLK_LAST / KEYBITS_WORD_BITS + 1];
 	// emulator keys should always be processed immediately lest one is lost
 	keybits_t emu_keys[SDLK_LAST / KEYBITS_WORD_BITS + 1];
@@ -259,6 +266,139 @@ static int get_keystate(keybits_t *keystate, int sym)
 	return !!(*ks_word & mask);
 }
 
+static inline void switch_key(SDL_Event *event, keybits_t *keystate, short upkey, short downkey)
+{
+	event->type = SDL_KEYUP;
+	event->key.state = SDL_RELEASED;
+	event->key.keysym.sym = upkey;
+
+	update_keystate(keystate, upkey, 0);
+	SDL_PushEvent(event);
+
+	event->type = SDL_KEYDOWN;
+	event->key.state = SDL_PRESSED;
+	event->key.keysym.sym = downkey;
+
+	update_keystate(keystate, downkey, 1);
+	SDL_PushEvent(event);
+}
+
+static void translate_combo_event(struct in_sdl_state *state, SDL_Event *event, keybits_t *keystate)
+{
+	const struct in_pdata *pdata = state->drv->pdata;
+	const struct mod_keymap *map;
+	short key = (short)event->key.keysym.sym;
+	uint8_t type  = event->type;
+	short mod_key = pdata->mod_key;
+	int i;
+
+	if (event->type != SDL_KEYDOWN && event->type != SDL_KEYUP) {
+		SDL_PushEvent(event);
+		return;
+	}
+
+	if (state->mod_state == MOD_NO && key != mod_key) {
+		update_keystate(keystate, event->key.keysym.sym, event->type == SDL_KEYDOWN);
+		SDL_PushEvent(event);
+		return;
+	}
+
+	if (key == mod_key) {
+		switch (state->mod_state) {
+		case MOD_NO:
+			if (type == SDL_KEYDOWN) {
+				/* Pressed mod, maybe a combo? Ignore the keypress
+				 * until it's determined */
+				state->mod_state = MOD_MAYBE;
+
+				for (i = 0; i < pdata->modmap_size; i++) {
+					map = &pdata->mod_keymap[i];
+
+					if (get_keystate(keystate, map->inkey)) {
+						state->mod_state = MOD_YES;
+						switch_key(event, keystate, map->inkey, map->outkey);
+					}
+				}
+			} else {
+				SDL_PushEvent(event);
+			}
+			break;
+		case MOD_MAYBE:
+			if (type == SDL_KEYDOWN) {
+				SDL_PushEvent(event);
+			} else {
+				/* Released mod without combo, simulate down and up */
+				state->mod_state = MOD_NO;
+
+				event->type = SDL_KEYDOWN;
+				event->key.state = SDL_PRESSED;
+				SDL_PushEvent(event);
+
+				event->type = SDL_KEYUP;
+				event->key.state = SDL_RELEASED;
+				SDL_PushEvent(event);
+			}
+			break;
+		case MOD_YES:
+			if (type == SDL_KEYDOWN) {
+				SDL_PushEvent(event);
+			} else {
+				/* Released mod, switch all mod keys to unmod and ignore mod press */
+				state->mod_state = MOD_NO;
+
+				for (i = 0; i < pdata->modmap_size; i++) {
+					map = &pdata->mod_keymap[i];
+
+					if (get_keystate(keystate, map->outkey)) {
+						switch_key(event, keystate, map->outkey, map->inkey);
+					}
+				}
+			}
+			break;
+		default:
+			SDL_PushEvent(event);
+			break;
+		}
+	} else {
+		for (i = 0; i < pdata->modmap_size; i++) {
+			map = &pdata->mod_keymap[i];
+
+			if (map->inkey == key) {
+				state->mod_state = MOD_YES;
+
+				event->key.keysym.sym = map->outkey;
+				update_keystate(keystate, map->outkey, event->type == SDL_KEYDOWN);
+				SDL_PushEvent(event);
+			}
+		}
+	}
+}
+
+static void translate_combo_events(struct in_sdl_state *state, Uint32 mask)
+{
+	const struct in_pdata *pdata = state->drv->pdata;
+	SDL_Event events[10]; /* Must be bigger than events size in collect_events */
+	keybits_t keystate[SDLK_LAST / KEYBITS_WORD_BITS + 1];
+	int count;
+	int has_events;
+	int i;
+
+	if (!pdata->mod_key)
+		return;
+
+	has_events = SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, mask);
+
+	if (!has_events)
+		return;
+
+	memcpy(keystate, state->keystate, sizeof(keystate));
+
+	count = SDL_PeepEvents(events, (sizeof(events) / sizeof(events[0])), SDL_GETEVENT, mask);
+	for (i = 0; i < count; i++) {
+		translate_combo_event(state, &events[i], keystate);
+	}
+}
+
 static int handle_event(struct in_sdl_state *state, SDL_Event *event,
 	int *kc_out, int *down_out, int *emu_out)
 {
@@ -363,6 +503,9 @@ static int collect_events(struct in_sdl_state *state, int *one_kc, int *one_down
 
 	SDL_PumpEvents();
 
+	if (!state->joy)
+		translate_combo_events(state, mask);
+
 	num_events = SDL_PeepEvents(NULL, 0, SDL_PEEKEVENT, mask);
 
 	for (num_peeped_events = 0; num_peeped_events < num_events; num_peeped_events += count) {
diff --git a/input.h b/input.h
index 360b65b..895ad61 100644
--- a/input.h
+++ b/input.h
@@ -110,6 +110,11 @@ struct menu_keymap {
 	short pbtn;
 };
 
+struct mod_keymap {
+	short inkey;
+	short outkey;
+};
+
 struct in_pdata {
 	const struct in_default_bind *defbinds;
 	const struct menu_keymap *key_map;
@@ -117,6 +122,9 @@ struct in_pdata {
 	const struct menu_keymap *joy_map;
 	size_t jmap_size;
 	const char * const *key_names;
+	short mod_key;
+	const struct mod_keymap *mod_keymap;
+	size_t modmap_size;
 };
 
 /* to be called by drivers */