diff --git a/lib/waterfoul.rb b/lib/waterfoul.rb
index 296068f..b9da885 100644
--- a/lib/waterfoul.rb
+++ b/lib/waterfoul.rb
@@ -9,7 +9,7 @@ require "waterfoul/cpu"
 require "waterfoul/errors"
 require "waterfoul/sdl"
 require "waterfoul/screen"
-require "waterfoul/gpu"
+require "waterfoul/ppu"
 require "waterfoul/cartridge"
 require "waterfoul/emulator"
 require "waterfoul/input"
diff --git a/lib/waterfoul/emulator.rb b/lib/waterfoul/emulator.rb
index a53247a..7902742 100644
--- a/lib/waterfoul/emulator.rb
+++ b/lib/waterfoul/emulator.rb
@@ -10,7 +10,7 @@ module Waterfoul
       @cartridge = Cartridge.new rom
       @cpu = CPU.new
       @cpu = SkipBoot.set_state(@cpu) if options.has_key?('skip_boot')
-      @gpu = GPU.new
+      @ppu = PPU.new
       @screen = Screen.new
     end
 
@@ -18,8 +18,8 @@ module Waterfoul
       $mmu.cartridge = @cartridge
       loop do
         @cpu.step
-        @gpu.step @cpu.m
-        @screen.render @gpu.framebuffer if @gpu.vblank?
+        @ppu.step @cpu.m
+        @screen.render @ppu.framebuffer if @ppu.vblank?
       end
     end
   end
diff --git a/lib/waterfoul/helper.rb b/lib/waterfoul/helper.rb
index eae555f..0119def 100644
--- a/lib/waterfoul/helper.rb
+++ b/lib/waterfoul/helper.rb
@@ -1,14 +1,10 @@
 module Waterfoul
   module Helper
-
     def pop_from_stack(word = true)
       if word
-        lower = $mmu.read_byte @sp
-        @sp += 1
-        upper = $mmu.read_byte @sp
-        @sp += 1
-
-        (upper << 8) | lower
+        val = $mmu.read_word @sp
+        @sp += 2
+        val
       else
         val = $mmu.read_byte @sp
         @sp += 1
diff --git a/lib/waterfoul/gpu.rb b/lib/waterfoul/ppu.rb
similarity index 99%
rename from lib/waterfoul/gpu.rb
rename to lib/waterfoul/ppu.rb
index 7921c77..5f944b8 100644
--- a/lib/waterfoul/gpu.rb
+++ b/lib/waterfoul/ppu.rb
@@ -1,7 +1,7 @@
 require 'waterfoul/io/lcd_control'
 
 module Waterfoul
-  class GPU
+  class PPU
     include Helper
 
     attr_accessor :mode