diff --git a/src/bit.ml b/src/bit.ml
index d6e50cc..38a3725 100644
--- a/src/bit.ml
+++ b/src/bit.ml
@@ -4,3 +4,9 @@ let is_set num i =
   else
     (num lsr i) land 0b00000001 <> 0
 
+let two_complement n =
+  (lnot n) + 1
+
+let signed_byte n =
+  if n land 0x80 <> 0 then -((two_complement n) land 0xFF)
+  else n
diff --git a/src/cpu.ml b/src/cpu.ml
index 784b988..e594efb 100644
--- a/src/cpu.ml
+++ b/src/cpu.ml
@@ -127,14 +127,6 @@ let pop_stack cpu mem =
   cpu.reg.sp <- (cpu.reg.sp + 1) mod 0xFFFF;
   merge_bytes low high
 
-let two_complement n =
-  (lnot n) + 1
-
-let signed_byte n =
-  if n land 0x80 <> 0 then -((two_complement n) land 0xFF)
-  else n
-
-
 
 (**
   http://imrannazar.com/GameBoy-Z80-Opcode-Map
@@ -172,7 +164,7 @@ let run cpu (mem: Memory.map) =
 
   (* jump *)
   | '\x20' -> let n = read_pc_byte cpu mem in
-              let s = signed_byte n in
+              let s = Bit.signed_byte n in
               let inst = sprintf "JR \tNZ, 0x%02X (%d)" n s in
               if cpu.flag.z = false then
               begin