diff --git a/lvgl_tft/ssd1306.c b/lvgl_tft/ssd1306.c
index 3336f8a..141cfde 100644
--- a/lvgl_tft/ssd1306.c
+++ b/lvgl_tft/ssd1306.c
@@ -95,7 +95,7 @@ static uint8_t send_pixels(lv_disp_drv_t *disp_drv, void *color_buffer, size_t b
 /**********************
  *   GLOBAL FUNCTIONS
  **********************/
-void ssd1306_init()
+void ssd1306_init(void)
 {
     uint8_t orientation_1 = 0;
     uint8_t orientation_2 = 0;
@@ -130,7 +130,7 @@ void ssd1306_init()
         OLED_CMD_DISPLAY_ON
     };
     
-    send_data(NULL, conf, sizeof conf);
+    send_data(NULL, conf, sizeof(conf));
 }
 
 void ssd1306_set_px_cb(lv_disp_drv_t * disp_drv, uint8_t * buf, lv_coord_t buf_w, lv_coord_t x, lv_coord_t y,
@@ -164,7 +164,7 @@ void ssd1306_flush(lv_disp_drv_t * disp_drv, const lv_area_t * area, lv_color_t
         row2,
     };
 
-    send_data(disp_drv, conf, sizeof conf);
+    send_data(disp_drv, conf, sizeof(conf));
     send_pixels(disp_drv, color_p, OLED_COLUMNS * (1 + row2 - row1));
 
     lv_disp_flush_ready(disp_drv);
@@ -176,24 +176,24 @@ void ssd1306_rounder(lv_disp_drv_t * disp_drv, lv_area_t *area)
     area->x2 = area->x2 | 0x07;
 }
 
-void ssd1306_sleep_in()
+void ssd1306_sleep_in(void)
 {
     uint8_t conf[] = {
         OLED_CONTROL_BYTE_CMD_STREAM,
         OLED_CMD_DISPLAY_OFF
     };
 
-    send_data(NULL, conf, sizeof conf);
+    send_data(NULL, conf, sizeof(conf));
 }
 
-void ssd1306_sleep_out()
+void ssd1306_sleep_out(void)
 {
     uint8_t conf[] = {
         OLED_CONTROL_BYTE_CMD_STREAM,
         OLED_CMD_DISPLAY_ON
     };
 
-    send_data(NULL, conf, sizeof conf);
+    send_data(NULL, conf, sizeof(conf));
 }
 
 /**********************