diff --git a/constants/BIOS_equ.inc b/constants/BIOS_equ.inc
index de5505e..89a22f4 100644
--- a/constants/BIOS_equ.inc
+++ b/constants/BIOS_equ.inc
@@ -153,6 +153,7 @@ ZX_MEMORY_MANAGER	EQU	#FC		; [ ] free zx pages!
 .GetMem.Pent128			EQU #02FC
 .GetMem.Pent512			EQU #03FC
 .GetMem.Scorp			EQU #04FC
+.SetCustomVroms			EQU #80FC
 ;
 .MODE_48k			EQU	3
 .MODE_128k			EQU	3+5