diff --git a/kernel/trunk/kernel.asm b/kernel/trunk/kernel.asm
index 44ee30c80..0f867dd3e 100644
--- a/kernel/trunk/kernel.asm
+++ b/kernel/trunk/kernel.asm
@@ -3289,8 +3289,11 @@ align 4
 ;--------------------------------------
 align 4
 mouse_not_active:
-        cmp     byte[REDRAW_BACKGROUND], 0         ; background update ?
+        xor     eax, eax
+        xchg    al, [REDRAW_BACKGROUND]
+        test    al, al      ; background update ?
         jz      nobackgr
+
         cmp     [background_defined], 0
         jz      nobackgr
 ;--------------------------------------