diff --git a/presets/nes/horizmask.c b/presets/nes/horizmask.c
index 19d764ed..66dbf605 100644
--- a/presets/nes/horizmask.c
+++ b/presets/nes/horizmask.c
@@ -76,7 +76,7 @@ void update_nametable() {
   // draw rest of building
   memset(buf+PLAYROWS-bldg_height, bldg_char, bldg_height);
   // draw vertical slice in name table
-  vrambuf_put(addr ^ 0xc000, buf, PLAYROWS);
+  vrambuf_put(addr | VRAMBUF_VERT, buf, PLAYROWS);
   // every 4 columns, update attribute table
   if ((x & 3) == 1) {
     // compute attribute table address
diff --git a/presets/nes/vrambuf.h b/presets/nes/vrambuf.h
index ba761d8c..0d26d7fe 100644
--- a/presets/nes/vrambuf.h
+++ b/presets/nes/vrambuf.h
@@ -23,6 +23,9 @@ extern byte updptr;
   VRAMBUF_ADD(addr);\
   VRAMBUF_ADD(len);
 
+// OR with address to put vertical run
+#define VRAMBUF_VERT	0x8000
+
 // add EOF marker to buffer (but don't increment pointer)
 void vrambuf_end(void);