diff --git a/boot1.s b/boot1.s
index ab16baa..c8b1149 100644
--- a/boot1.s
+++ b/boot1.s
@@ -382,7 +382,7 @@ vga_clear:
   push ax
   push cx
 
-  mov ax, 0xb800
+  mov ax, VGA_SEG
   mov es, ax
   mov ax, [GLOBALS + VGA_COL]
   mov cx, VGA_WIDTH * VGA_HEIGHT
@@ -410,7 +410,7 @@ vga_scroll:
   push es
   push ds
 
-  mov ax, 0xb800
+  mov ax, VGA_SEG
   mov ds, ax
   mov es, ax
 
@@ -475,7 +475,7 @@ vga_print_raw:
   mov di, cx
   shl di, 1
   
-  mov ax, 0xb800
+  mov ax, VGA_SEG
   mov fs, ax
   mov ah, [GLOBALS + VGA_COL + 1]
 
diff --git a/defines.s b/defines.s
index c77ed10..d46b3a4 100644
--- a/defines.s
+++ b/defines.s
@@ -12,6 +12,8 @@
 
 %define EBDA_START 0x080000
 
+%define VGA_SEG 0xb800
+
 %define BOOT1_MAGIC 0x544e4150
 
 %define VGA_WIDTH  80