diff --git a/lib/waterfoul/cpu.rb b/lib/waterfoul/cpu.rb
index 2a94ce9..ac263e6 100644
--- a/lib/waterfoul/cpu.rb
+++ b/lib/waterfoul/cpu.rb
@@ -78,7 +78,7 @@ module Waterfoul
     end
 
     def check_halt
-      @halt = false if @pre_halt_interrupt != $mmu.read_byte(0xFF0F)
+      @halt = false if @pre_halt_interrupt != $mmu.read_memory_byte(0xFF0F)
     end
 
     def halted?
diff --git a/lib/waterfoul/mmu.rb b/lib/waterfoul/mmu.rb
index c299866..3ffbdcf 100644
--- a/lib/waterfoul/mmu.rb
+++ b/lib/waterfoul/mmu.rb
@@ -81,6 +81,10 @@ module Waterfoul
     alias_method :write_byte, :[]=
     alias_method :read_byte, :[]
 
+    def read_memory_byte(i)
+      @memory[i]
+    end
+
     # read 2 bytes from memory
     def read_word(addr)
       self[addr] | (self[addr + 1] << 8)
diff --git a/lib/waterfoul/ppu.rb b/lib/waterfoul/ppu.rb
index 4d07a16..cca7638 100644
--- a/lib/waterfoul/ppu.rb
+++ b/lib/waterfoul/ppu.rb
@@ -304,7 +304,7 @@ module Waterfoul
             pixel = (byte_1 & (0x1 << (7 - pixelx)) > 0) ? 1 : 0
             pixel |= (byte_2 & (0x1 << (7 - pixelx)) > 0) ? 2 : 0
             position = line_width + buffer_addr
-            palette = $mmu.read_byte 0xFF47
+            palette = $mmu.read_memory_byte 0xFF47
             color = (palette >> (pixel * 2)) & 0x3
 
             @framebuffer[position] = rgb(color)