diff --git a/src/cpu.ml b/src/cpu.ml
index d2dc4e9..776e696 100644
--- a/src/cpu.ml
+++ b/src/cpu.ml
@@ -93,15 +93,23 @@ let cmp_A cpu n =
   cpu.flag.c <- diff > 0xFF || diff < 0;
   update_flag_reg cpu
 
+let read_pc_byte cpu mem =
+  let b = Memory.get mem cpu.reg.pc in
+  inc_pc cpu 1;
+  int_of_char b
+  
+let read_pc_2bytes cpu mem =
+  let word = read_2B mem cpu.reg.pc in
+  inc_pc cpu 2;
+  word
+
+
 (**
   http://imrannazar.com/GameBoy-Z80-Opcode-Map
   https://github.com/sinamas/gambatte/blob/master/libgambatte/src/cpu.cpp
 *)
 let run cpu (mem: Memory.map) =
-  let opcode = Memory.get mem cpu.reg.pc in
-  inc_pc cpu 1;
-  let n = Memory.get mem cpu.reg.pc |> int_of_char in
-  let nn = Memory.get mem (cpu.reg.pc + 1) |> int_of_char in
+  let opcode = read_pc_byte cpu mem |> char_of_int in
 (*  Hexa.print_slice cartridge.full_rom cpu.reg.pc (cpu.reg.pc + 7); *)
   match opcode with
   | '\x00' -> printf "  NOP\n";
@@ -111,38 +119,43 @@ let run cpu (mem: Memory.map) =
               inc_BC cpu;
               inc_cycles cpu 8
 
-  | '\x18' -> printf "  JP\t 0x%02X\n" n;
-              inc_pc cpu n; inc_cycles cpu 12
+  | '\x18' -> let n = read_pc_byte cpu mem in
+              printf "  JP\t 0x%02X\n" n;
+              inc_pc cpu (n - 1); inc_cycles cpu 12
 
-  | '\x20' -> printf "  JR\t NZ, 0x%02X\n" n;
+  | '\x20' -> let n = read_pc_byte cpu mem in
+              printf "  JR\t NZ, 0x%02X\n" n;
               if cpu.flag.z = false then
               begin
-                inc_pc cpu n; inc_cycles cpu 12
+                inc_pc cpu (n - 1); inc_cycles cpu 12
               end else
               begin
-                inc_pc cpu 1; inc_cycles cpu 8
+                inc_cycles cpu 8
               end
 
-  | '\x21' -> let addr = read_2B mem cpu.reg.pc in
-              printf "  LD\t HL, 0x%04X\n" addr;
-              cpu.reg.h <- char_of_int nn;
-              cpu.reg.l <- char_of_int n;
+  | '\x21' -> let nn = read_pc_2bytes cpu mem in
+              printf "  LD\t HL, 0x%04X\n" nn;
+              let high, low = split_2B nn in
+              cpu.reg.h <- high;
+              cpu.reg.l <- low;
               inc_cycles cpu 12
 
 
-  | '\x28' -> printf "  JR\t Z, 0x%02X\n" n;
+  | '\x28' -> let n = read_pc_byte cpu mem in
+              printf "  JR\t Z, 0x%02X\n" n;
               if cpu.flag.z = true then
               begin
-                inc_pc cpu n; inc_cycles cpu 12
+                inc_pc cpu (n - 1); inc_cycles cpu 12
               end else
               begin
-                inc_pc cpu 1; inc_cycles cpu 8
+                inc_cycles cpu 8
               end
 
 
-  | '\x3E' -> printf "  LD \tA, 0x%02X\n" n;
-              cpu.reg.a <- char_of_int(n);
-              inc_pc cpu 1; inc_cycles cpu 8
+  | '\x3E' -> let n = read_pc_byte cpu mem in
+              printf "  LD \tA, 0x%02X\n" n;
+              cpu.reg.a <- char_of_int n;
+              inc_cycles cpu 8
 
   | '\xAF' -> printf "  XOR \tA, A\n";
               let int_A = int_of_char cpu.reg.a in
@@ -157,25 +170,28 @@ let run cpu (mem: Memory.map) =
               end else
                 inc_cycles cpu 8
 
-  | '\xC3' -> let addr = read_2B mem cpu.reg.pc in
+  | '\xC3' -> let addr = read_pc_2bytes cpu mem in
               printf "  JP \t0x%04X\n" addr;
               cpu.reg.pc <- addr; inc_cycles cpu 16
 
-  | '\xE0' -> printf "  LDH \t(0xFF%02X), A\n" n;
+  | '\xE0' -> let n = read_pc_byte cpu mem in
+              printf "  LDH \t(0xFF%02X), A\n" n;
               Memory.set mem (0xFF00 + n) cpu.reg.a;
-              inc_pc cpu 1; inc_cycles cpu 12
+              inc_cycles cpu 12
 
-  | '\xF0' -> printf "  LDH \tA, (0xFF%02X)\n" n;
+  | '\xF0' -> let n = read_pc_byte cpu mem in
+              printf "  LDH \tA, (0xFF%02X)\n" n;
               cpu.reg.a <- Memory.get mem (0xFF00 + n);
-              inc_pc cpu 1; inc_cycles cpu 12
+              inc_cycles cpu 12
 
   | '\xF3' -> printf "  DI\n";
               (* fixme *)
               inc_cycles cpu 4
 
-  | '\xFE' -> printf "  CP\t0x%02X\n" n;
+  | '\xFE' -> let n = read_pc_byte cpu mem in
+              printf "  CP\t0x%02X\n" n;
               cmp_A cpu n;
-              inc_pc cpu 1; inc_cycles cpu 8
+              inc_cycles cpu 8
 
   |  x -> eprintf "opcode 0x%02X\n" (int_of_char x);
           failwith "Unimplemented opcode."