diff --git a/src/gui.c b/src/gui.c
index 0523f01..d6981f9 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -11,6 +11,9 @@
 #include "display.h"     /* LCD_HEIGHT; LCD_WIDTH; shouldRender; lcdScreenGS[] */
 #include "persistence.h" /* load_file_on_stack(); */
 
+/***********/
+/* DEFINES */
+/***********/
 #define PANEL_FLAG_VISIBLE 0x01
 
 #define UI_PADDING 4
@@ -54,6 +57,9 @@
 // Releaseing mouse button 1 anywhere unpushes the button
 #define BUTTON_B1RELEASE 0x10
 
+/***********/
+/* TYPEDEF */
+/***********/
 typedef struct {
     int index;
     int x, y;
@@ -79,6 +85,9 @@ typedef struct {
     SDL_Color below;
 } colors_t;
 
+/*************/
+/* VARIABLES */
+/*************/
 static TTF_Font* ttffont = NULL;
 static TTF_Font* ttffont2 = NULL;
 
@@ -734,6 +743,9 @@ static SDL_Color pixels_colors[] = {
     {.r = 37,  .g = 61,  .b = 84,  .a = 255},
 };
 
+/*************/
+/* FUNCTIONS */
+/*************/
 static inline bool _init_keyboard_textures()
 {
     SDL_Surface* s = NULL;
@@ -956,6 +968,9 @@ static inline void button_draw_all()
         _button_draw( gui_buttons[ i ] );
 }
 
+/********************/
+/* PUBLIC FUNCTIONS */
+/********************/
 void gui_refresh()
 {
     SDL_SetRenderDrawColor( renderer, gui_colors.faceplate.r, gui_colors.faceplate.g, gui_colors.faceplate.b, gui_colors.faceplate.a );
diff --git a/src/persistence.c b/src/persistence.c
index 66f1279..94604c6 100644
--- a/src/persistence.c
+++ b/src/persistence.c
@@ -436,38 +436,38 @@ void rom_init( char* filename )
 
     size = file_size( fullpath );
     if ( !size ) {
-        printf( "ERROR: Can't read ROM file size\n" );
+        fprintf( stderr, "ERROR: Can't read ROM file size\n" );
         exit( 0x10 );
     }
     if ( size != 256 * 1024 && size != 512 * 1024 && size != 1024 * 1024 ) {
-        printf( "ERROR: ROM file size invalid\n" );
+        fprintf( stderr, "ERROR: ROM file size invalid\n" );
         exit( 0x11 );
     }
     buf = malloc( size );
     if ( !buf ) {
-        printf( "ERROR: can't malloc ROM\n" );
+        fprintf( stderr, "ERROR: can't malloc ROM\n" );
         exit( 0x12 );
     }
 
     f = fopen( fullpath, "r" );
     if ( !f ) {
-        printf( "ERROR: can't open ROM file\n" );
+        fprintf( stderr, "ERROR: can't open ROM file\n" );
         exit( 0x13 );
     }
     if ( ( int )fread( buf, sizeof( char ), size, f ) != size ) { // pack_fread
-        printf( "ERROR: can't read ROM file\n" );
+        fprintf( stderr, "ERROR: can't read ROM file\n" );
         exit( 0x14 );
     }
     fclose( f );
 
     if ( buf[ 0 ] & 0xF0 || buf[ 1 ] & 0xF0 ) {
         if ( size == 1024 * 1024 ) {
-            printf( "ERROR: wrong ROM\n" );
+            fprintf( stderr, "ERROR: wrong ROM\n" );
             exit( 0x15 );
         }
         buf = realloc( buf, size * 2 );
         if ( !buf ) {
-            printf( "ERROR: can't realloc ROM\n" );
+            fprintf( stderr, "ERROR: can't realloc ROM\n" );
             exit( 0x16 );
         }
         ptr1 = buf + size - 1;
@@ -480,7 +480,6 @@ void rom_init( char* filename )
     }
     bus_info.rom_data = buf;
     bus_info.rom_mask = size - 1;
-    printf( "rom_init succeed!\n" );
 }
 
 void rom_exit( void )