diff --git a/lib/waterfoul/mmu.rb b/lib/waterfoul/mmu.rb
index 84a03cc..863118d 100644
--- a/lib/waterfoul/mmu.rb
+++ b/lib/waterfoul/mmu.rb
@@ -73,7 +73,7 @@ module Waterfoul
         when 0xFF46 # DMA transfer
           dma_transfer v
         when 0xFF04 # reset divider register
-          self[i] = 0
+          @memory[i] = 0
         else
           @memory[i] = v
         end