diff --git a/src/test/java/dk/camelot64/kickc/test/kc/c64.kc b/src/test/java/dk/camelot64/kickc/test/kc/c64.kc
index 8268301a9..af47a8cdb 100644
--- a/src/test/java/dk/camelot64/kickc/test/kc/c64.kc
+++ b/src/test/java/dk/camelot64/kickc/test/kc/c64.kc
@@ -55,13 +55,20 @@ const byte VIC_CSEL = %00001000;
 const byte* D018 = $d018;
 const byte* VIC_MEMORY = $d018;
 
+const byte* LIGHTPEN_X = $d013;
+const byte* LIGHTPEN_Y = $d014;
+
+// VIC II IRQ Status Register
 const byte* IRQ_STATUS = $d019;
+// VIC II IRQ Enable Register
 const byte* IRQ_ENABLE = $d01a;
+// Bits for the IRQ Status/Enable Registers
 const byte IRQ_RASTER = %00000001;
 const byte IRQ_COLLISION_BG = %00000010;
 const byte IRQ_COLLISION_SPRITE = %00000100;
 const byte IRQ_LIGHTPEN = %00001000;
 
+// Color Ram
 const byte* COLS = $d800;
 
 // CIA#1 Port A: keyboard matrix columns and joystick #2