diff --git a/app/src/control.c b/app/src/control.c
index 0b072dff..ece452da 100644
--- a/app/src/control.c
+++ b/app/src/control.c
@@ -28,7 +28,7 @@ void controller_destroy(struct controller *controller) {
     control_event_queue_destroy(&controller->queue);
 }
 
-SDL_bool controller_push_event(struct controller *controller, struct control_event *event) {
+SDL_bool controller_push_event(struct controller *controller, const struct control_event *event) {
     SDL_bool res;
     mutex_lock(controller->mutex);
     SDL_bool was_empty = control_event_queue_is_empty(&controller->queue);
@@ -40,7 +40,7 @@ SDL_bool controller_push_event(struct controller *controller, struct control_eve
     return res;
 }
 
-static SDL_bool process_event(struct controller *controller, struct control_event *event) {
+static SDL_bool process_event(struct controller *controller, const struct control_event *event) {
     unsigned char serialized_event[SERIALIZED_EVENT_MAX_SIZE];
     int length = control_event_serialize(event, serialized_event);
     if (!length) {
diff --git a/app/src/control.h b/app/src/control.h
index 3efd14f9..14b93a2a 100644
--- a/app/src/control.h
+++ b/app/src/control.h
@@ -24,6 +24,6 @@ void controller_stop(struct controller *controller);
 void controller_join(struct controller *controller);
 
 // expose simple API to hide control_event_queue
-SDL_bool controller_push_event(struct controller *controller, struct control_event *event);
+SDL_bool controller_push_event(struct controller *controller, const struct control_event *event);
 
 #endif
diff --git a/app/src/controlevent.c b/app/src/controlevent.c
index fda49d11..9436139a 100644
--- a/app/src/controlevent.c
+++ b/app/src/controlevent.c
@@ -17,7 +17,7 @@ static inline void write32(Uint8 *buf, Uint32 value) {
     buf[3] = value;
 }
 
-int control_event_serialize(struct control_event *event, unsigned char *buf) {
+int control_event_serialize(const struct control_event *event, unsigned char *buf) {
     buf[0] = event->type;
     switch (event->type) {
     case CONTROL_EVENT_TYPE_KEYCODE:
@@ -53,11 +53,11 @@ int control_event_serialize(struct control_event *event, unsigned char *buf) {
     }
 }
 
-SDL_bool control_event_queue_is_empty(struct control_event_queue *queue) {
+SDL_bool control_event_queue_is_empty(const struct control_event_queue *queue) {
     return queue->head == queue->tail;
 }
 
-SDL_bool control_event_queue_is_full(struct control_event_queue *queue) {
+SDL_bool control_event_queue_is_full(const struct control_event_queue *queue) {
     return (queue->head + 1) % CONTROL_EVENT_QUEUE_SIZE == queue->tail;
 }
 
@@ -72,7 +72,7 @@ void control_event_queue_destroy(struct control_event_queue *queue) {
     // nothing to do in the current implementation
 }
 
-SDL_bool control_event_queue_push(struct control_event_queue *queue, struct control_event *event) {
+SDL_bool control_event_queue_push(struct control_event_queue *queue, const struct control_event *event) {
     if (control_event_queue_is_full(queue)) {
         return SDL_FALSE;
     }
diff --git a/app/src/controlevent.h b/app/src/controlevent.h
index 0c4d1f03..d0534ed2 100644
--- a/app/src/controlevent.h
+++ b/app/src/controlevent.h
@@ -51,16 +51,16 @@ struct control_event_queue {
 };
 
 // buf size must be at least SERIALIZED_EVENT_MAX_SIZE
-int control_event_serialize(struct control_event *event, unsigned char *buf);
+int control_event_serialize(const struct control_event *event, unsigned char *buf);
 
 SDL_bool control_event_queue_init(struct control_event_queue *queue);
 void control_event_queue_destroy(struct control_event_queue *queue);
 
-SDL_bool control_event_queue_is_empty(struct control_event_queue *queue);
-SDL_bool control_event_queue_is_full(struct control_event_queue *queue);
+SDL_bool control_event_queue_is_empty(const struct control_event_queue *queue);
+SDL_bool control_event_queue_is_full(const struct control_event_queue *queue);
 
 // event is copied, the queue does not use the event after the function returns
-SDL_bool control_event_queue_push(struct control_event_queue *queue, struct control_event *event);
+SDL_bool control_event_queue_push(struct control_event_queue *queue, const struct control_event *event);
 SDL_bool control_event_queue_take(struct control_event_queue *queue, struct control_event *event);
 
 #endif
diff --git a/app/src/convert.c b/app/src/convert.c
index 0c5cf163..c063a078 100644
--- a/app/src/convert.c
+++ b/app/src/convert.c
@@ -117,7 +117,7 @@ static enum android_motionevent_buttons convert_mouse_buttons(Uint32 state) {
     return buttons;
 }
 
-SDL_bool input_key_from_sdl_to_android(SDL_KeyboardEvent *from, struct control_event *to) {
+SDL_bool input_key_from_sdl_to_android(const SDL_KeyboardEvent *from, struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_KEYCODE;
 
     if (!convert_keycode_action(from->type, &to->keycode_event.action)) {
@@ -133,7 +133,7 @@ SDL_bool input_key_from_sdl_to_android(SDL_KeyboardEvent *from, struct control_e
     return SDL_TRUE;
 }
 
-SDL_bool mouse_button_from_sdl_to_android(SDL_MouseButtonEvent *from, struct control_event *to) {
+SDL_bool mouse_button_from_sdl_to_android(const SDL_MouseButtonEvent *from, struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_MOUSE;
 
     if (!convert_mouse_action(from->type, &to->mouse_event.action)) {
@@ -147,7 +147,7 @@ SDL_bool mouse_button_from_sdl_to_android(SDL_MouseButtonEvent *from, struct con
     return SDL_TRUE;
 }
 
-SDL_bool mouse_motion_from_sdl_to_android(SDL_MouseMotionEvent *from, struct control_event *to) {
+SDL_bool mouse_motion_from_sdl_to_android(const SDL_MouseMotionEvent *from, struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_MOUSE;
     to->mouse_event.action = AMOTION_EVENT_ACTION_MOVE;
     to->mouse_event.buttons = convert_mouse_buttons(from->state);
@@ -157,7 +157,7 @@ SDL_bool mouse_motion_from_sdl_to_android(SDL_MouseMotionEvent *from, struct con
     return SDL_TRUE;
 }
 
-SDL_bool mouse_wheel_from_sdl_to_android(struct complete_mouse_wheel_event *from, struct control_event *to) {
+SDL_bool mouse_wheel_from_sdl_to_android(const struct complete_mouse_wheel_event *from, struct control_event *to) {
     to->type = CONTROL_EVENT_TYPE_SCROLL;
 
     to->scroll_event.x = from->x;
diff --git a/app/src/convert.h b/app/src/convert.h
index 03d3f3aa..12a89ad3 100644
--- a/app/src/convert.h
+++ b/app/src/convert.h
@@ -12,9 +12,9 @@ struct complete_mouse_wheel_event {
     Sint32 y;
 };
 
-SDL_bool input_key_from_sdl_to_android(SDL_KeyboardEvent *from, struct control_event *to);
-SDL_bool mouse_button_from_sdl_to_android(SDL_MouseButtonEvent *from, struct control_event *to);
-SDL_bool mouse_motion_from_sdl_to_android(SDL_MouseMotionEvent *from, struct control_event *to);
-SDL_bool mouse_wheel_from_sdl_to_android(struct complete_mouse_wheel_event *from, struct control_event *to);
+SDL_bool input_key_from_sdl_to_android(const SDL_KeyboardEvent *from, struct control_event *to);
+SDL_bool mouse_button_from_sdl_to_android(const SDL_MouseButtonEvent *from, struct control_event *to);
+SDL_bool mouse_motion_from_sdl_to_android(const SDL_MouseMotionEvent *from, struct control_event *to);
+SDL_bool mouse_wheel_from_sdl_to_android(const struct complete_mouse_wheel_event *from, struct control_event *to);
 
 #endif
diff --git a/app/src/screen.c b/app/src/screen.c
index efc756c1..2c749c89 100644
--- a/app/src/screen.c
+++ b/app/src/screen.c
@@ -203,8 +203,7 @@ static inline SDL_bool prepare_for_frame(SDL_Window *window, SDL_Renderer *rende
     return SDL_TRUE;
 }
 
-
-static void update_texture(AVFrame *frame, SDL_Texture *texture) {
+static void update_texture(const AVFrame *frame, SDL_Texture *texture) {
     SDL_UpdateYUVTexture(texture, NULL,
             frame->data[0], frame->linesize[0],
             frame->data[1], frame->linesize[1],
@@ -258,7 +257,7 @@ static SDL_bool handle_new_frame(void) {
     return SDL_TRUE;
 }
 
-static void handle_text_input(SDL_TextInputEvent *event) {
+static void handle_text_input(const SDL_TextInputEvent *event) {
     struct control_event control_event;
     control_event.type = CONTROL_EVENT_TYPE_TEXT;
     strncpy(control_event.text_event.text, event->text, TEXT_MAX_LENGTH);
@@ -268,7 +267,7 @@ static void handle_text_input(SDL_TextInputEvent *event) {
     }
 }
 
-static void handle_key(SDL_KeyboardEvent *event) {
+static void handle_key(const SDL_KeyboardEvent *event) {
     SDL_Keycode keycode = event->keysym.sym;
     SDL_bool ctrl = event->keysym.mod & (KMOD_LCTRL | KMOD_RCTRL);
     SDL_bool shift = event->keysym.mod & (KMOD_LSHIFT | KMOD_RSHIFT);
@@ -305,7 +304,7 @@ static void handle_key(SDL_KeyboardEvent *event) {
     }
 }
 
-static void handle_mouse_motion(SDL_MouseMotionEvent *event) {
+static void handle_mouse_motion(const SDL_MouseMotionEvent *event) {
     struct control_event control_event;
     if (mouse_motion_from_sdl_to_android(event, &control_event)) {
         if (!controller_push_event(&controller, &control_event)) {
@@ -314,7 +313,7 @@ static void handle_mouse_motion(SDL_MouseMotionEvent *event) {
     }
 }
 
-static void handle_mouse_button(SDL_MouseButtonEvent *event) {
+static void handle_mouse_button(const SDL_MouseButtonEvent *event) {
     struct control_event control_event;
     if (mouse_button_from_sdl_to_android(event, &control_event)) {
         if (!controller_push_event(&controller, &control_event)) {
@@ -323,7 +322,7 @@ static void handle_mouse_button(SDL_MouseButtonEvent *event) {
     }
 }
 
-static void handle_mouse_wheel(struct complete_mouse_wheel_event *event) {
+static void handle_mouse_wheel(const struct complete_mouse_wheel_event *event) {
     struct control_event control_event;
     if (mouse_wheel_from_sdl_to_android(event, &control_event)) {
         if (!controller_push_event(&controller, &control_event)) {