diff --git a/src/vcpu.c b/src/vcpu.c
index 4ca5cc1..45b9aca 100644
--- a/src/vcpu.c
+++ b/src/vcpu.c
@@ -57,7 +57,7 @@ void VCPUExecute(){
   case 0xD:
     int X=State.V[State.X]%63;
     int Y=State.V[State.Y]%31;
-    State.V[0xF]=0; // Set flag to 0
+    State.V[REG_FLAG]=0; // Set flag to 0
     for(char row=0;row<State.N;row++){
       
     }
diff --git a/src/vcpu.h b/src/vcpu.h
index 33a1492..bd4d2d5 100644
--- a/src/vcpu.h
+++ b/src/vcpu.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#define REG_FLAG 0xF
+
 typedef struct VCPU_State {
   // Program Counter (16 bits but only 12 bits used (4096 memory addresses))
   unsigned short PC;