diff --git a/src/engine.c b/src/engine.c
index 2cb62b63..5c9bdd59 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -227,7 +227,7 @@ void Draw_menu_button(byte btn_number,byte pressed)
   word y_pos;
   byte current_menu;
   byte color;
-  char icon;
+  signed char icon;
 
   // Find in which menu the button is
   for (current_menu = 0; current_menu < MENUBAR_COUNT; current_menu++)
diff --git a/src/global.h b/src/global.h
index 3746126b..2b6b9ee8 100644
--- a/src/global.h
+++ b/src/global.h
@@ -581,7 +581,7 @@ GFX2_GLOBAL struct
   word            Height;           ///< Button's active heigth
   byte            Pressed;          ///< Button is currently pressed
   byte            Shape;            ///< Shape, listed in enum ::BUTTON_SHAPES
-  char            Icon;             ///< Which icon to display: Either the one from the toolbar (-1) or one of ::MENU_SPRITE
+  signed char     Icon;             ///< Which icon to display: Either the one from the toolbar (-1) or one of ::MENU_SPRITE
 
   // Triggers on mouse/keyboard
   Func_action     Left_action;      ///< Action triggered by a left mouseclick on the button