diff --git a/bun.c b/bun.c
index 6c3f7c1..cc0222c 100644
--- a/bun.c
+++ b/bun.c
@@ -13,6 +13,7 @@
 #include "screen.h"
 #include "bun.h"
 #include "system/system.h"
+#include "system/blitter.h"
 
 #define COOL_BUN_WIDTH (32)
 #define COOL_BUN_WIDTH_BYTES (COOL_BUN_WIDTH / 8)
@@ -40,16 +41,8 @@
 // linked as raw bytes in assembler
 extern unsigned char chip coolbun[];
 
-#define BLTCON0( \
-  minterm, aChan, bChan, cChan, dChan, shift \
-) (minterm + (aChan << 11) + (bChan << 10) + (cChan << 9) + (dChan << 8) + (shift << 12))
-#define BLTCON1(descending, shift) ((descending << 1) + (shift << 12))
-
 extern struct Custom far custom;
 
-#define BLITTER_ASCENDING (0)
-#define BLITTER_DESCENDING (1)
-
 struct BunClear {
   uint16_t memoryStartOffsetBytes;
   uint16_t widthWords;
@@ -373,7 +366,7 @@ void clearCurrentBuns(
 
   if (!hasBunClear[bunRenderer->activeScreenBufferDetails->currentBuffer]) return;
 
-  bltcon0 = 0xc0 + (1 << 8);
+  bltcon0 = BLTCON0(0xc0, 0, 0, 0, 1, 0);
 
   for (bun = 0; bun < BUN_COUNT; ++bun) {
     currentBunClear = &bunClearForScreen[bunRenderer->activeScreenBufferDetails->currentBuffer][bun];
diff --git a/main.c b/main.c
index 83e81f9..0779113 100644
--- a/main.c
+++ b/main.c
@@ -29,6 +29,16 @@
 #include "types.h"
 #include "bun.h"
 
+/**
+ * This barely gets 50fps but I'm leaving it for now. Potential improvements:
+ *
+ * [ ] Topaz re-rendering is limited to squares or rows that changed in the last frame.
+ *     I tried this once but I need a more precise way of redrawing those areas.
+ * [ ] Cool bun clears and re-renders happen in the same pass.
+ *     This would likely mean extending the cool bun art to have a blank word on the left,
+ *     and enough blank rows above and below to cover clearing areas above and below.
+ */
+
 extern struct Custom far custom;
 extern struct CIA far ciaa;
 
@@ -61,20 +71,17 @@ extern uint8_t chip MaskBitplane[];
 #define TOPAZ_WIDTH_BYTES (TOPAZ_WIDTH_PIXELS / 8)
 #define TOPAZ_WIDTH_WORDS (TOPAZ_WIDTH_PIXELS / 16)
 
-#define BLTSIZE(w, h) (w + (h << 6))
-
 void renderTopaz(void) {
   int plane;
 
-  uint16_t bltcon0, bltcmod;
+  uint16_t bltcmod;
   uint8_t *bltbpt;
 
-  bltcon0 = 0xca + (1 << 8) + (1 << 9) + (1 << 10) + (1 << 11);
   bltcmod = screenDefinition.byteWidth - TOPAZ_WIDTH_BYTES;
   bltbpt = TopazBitplanes;
 
   for (plane = 0; plane < 3; ++plane) {
-    custom.bltcon0 = bltcon0;
+    custom.bltcon0 = BLTCON0(0xca, 1, 1, 1, 1, 0);
     custom.bltcon1 = 0;
     custom.bltafwm = 0xffff;
     custom.bltalwm = 0xffff;
@@ -99,15 +106,14 @@ void renderTopaz(void) {
 void renderMostlyTopaz(void) {
   int plane;
 
-  uint16_t bltcon0, bltcmod;
+  uint16_t bltcmod;
   uint8_t *bltbpt;
 
-  bltcon0 = 0xca + (1 << 8) + (1 << 9) + (1 << 10) + (1 << 11);
   bltcmod = screenDefinition.byteWidth - TOPAZ_WIDTH_BYTES;
   bltbpt = TopazBitplanes;
 
   for (plane = 0; plane < 2; ++plane) {
-    custom.bltcon0 = bltcon0;
+    custom.bltcon0 = BLTCON0(0xca, 1, 1, 1, 1, 0);
     custom.bltcon1 = 0;
     custom.bltafwm = 0xffff;
     custom.bltalwm = 0xffff;
diff --git a/system/blitter.h b/system/blitter.h
index 6cb5d92..e8d7bd8 100644
--- a/system/blitter.h
+++ b/system/blitter.h
@@ -1,8 +1,14 @@
 #ifndef __BLITTER_H__
 #define __BLITTER_H__
 
-#include "types.h"
-#include "screen.h"
+#define BLTSIZE(w, h) (w + (h << 6))
+#define BLTCON0( \
+  minterm, aChan, bChan, cChan, dChan, shift \
+) (minterm + (aChan << 11) + (bChan << 10) + (cChan << 9) + (dChan << 8) + (shift << 12))
+#define BLTCON1(descending, shift) ((descending << 1) + (shift << 12))
+
+#define BLITTER_ASCENDING (0)
+#define BLITTER_DESCENDING (1)
 
 
 /*