diff --git a/pyproject.toml b/pyproject.toml
index ae6212f..388e112 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@
 
 [project]
 name = "mapfile_parser"
-version = "1.1.5"
+version = "1.2.0.dev0"
 description = "Map file parser library focusing decompilation projects"
 readme = "README.md"
 requires-python = ">=3.7"
diff --git a/src/mapfile_parser/__init__.py b/src/mapfile_parser/__init__.py
index f67d555..fd809b5 100644
--- a/src/mapfile_parser/__init__.py
+++ b/src/mapfile_parser/__init__.py
@@ -5,8 +5,8 @@
 
 from __future__ import annotations
 
-__version_info__ = (1, 1, 5)
-__version__ = ".".join(map(str, __version_info__))
+__version_info__ = (1, 2, 0)
+__version__ = ".".join(map(str, __version_info__)) + ".dev0"
 __author__ = "Decompollaborate"
 
 from . import utils
diff --git a/src/mapfile_parser/frontends/first_diff.py b/src/mapfile_parser/frontends/first_diff.py
index c3069db..0e25857 100644
--- a/src/mapfile_parser/frontends/first_diff.py
+++ b/src/mapfile_parser/frontends/first_diff.py
@@ -7,12 +7,13 @@
 
 import argparse
 from pathlib import Path
+from typing import Callable
 
 from .. import mapfile
 from .. import utils
 
 
-def doFirstDiff(mapPath: Path, expectedMapPath: Path, romPath: Path, expectedRomPath: Path, diffCount: int=5, mismatchSize: bool=False) -> int:
+def doFirstDiff(mapPath: Path, expectedMapPath: Path, romPath: Path, expectedRomPath: Path, diffCount: int=5, mismatchSize: bool=False, bytesConverterCallback:Callable[[bytes, mapfile.MapFile],str|None]|None=None) -> int:
     if not mapPath.exists():
         print(f"{mapPath} must exist")
         return 1
@@ -61,7 +62,14 @@ def doFirstDiff(mapPath: Path, expectedMapPath: Path, romPath: Path, expectedRom
                 if vromInfo is not None:
                     extraMessage = f", {vromInfo.getAsStrPlusOffset()}"
                 print(f"First difference at ROM addr 0x{i:X}{extraMessage}")
-                print(f"Bytes: {utils.hexbytes(builtRom[i : i + 4])} vs {utils.hexbytes(expectedRom[i : i + 4])}")
+                builtBytes = builtRom[i : i + 4]
+                expectedBytes = expectedRom[i : i + 4]
+                print(f"Bytes: {utils.hexbytes(builtBytes)} vs {utils.hexbytes(expectedBytes)}")
+                if bytesConverterCallback is not None:
+                    builtConverted = bytesConverterCallback(builtBytes, builtMapFile)
+                    expectedConverted = bytesConverterCallback(expectedBytes, expectedMapFile)
+                    if builtConverted is not None and expectedConverted is not None:
+                        print(f"{builtConverted} vs {expectedConverted}")
             diffs += 1
 
         if (
@@ -78,7 +86,14 @@ def doFirstDiff(mapPath: Path, expectedMapPath: Path, romPath: Path, expectedRom
                     if vromInfo is not None:
                         extraMessage = f", {vromInfo.getAsStrPlusOffset()}"
                     print(f"Instruction difference at ROM addr 0x{i:X}{extraMessage}")
-                    print(f"Bytes: {utils.hexbytes(builtRom[i : i + 4])} vs {utils.hexbytes(expectedRom[i : i + 4])}")
+                    builtBytes = builtRom[i : i + 4]
+                    expectedBytes = expectedRom[i : i + 4]
+                    print(f"Bytes: {utils.hexbytes(builtBytes)} vs {utils.hexbytes(expectedBytes)}")
+                    if bytesConverterCallback is not None:
+                        builtConverted = bytesConverterCallback(builtBytes, builtMapFile)
+                        expectedConverted = bytesConverterCallback(expectedBytes, expectedMapFile)
+                        if builtConverted is not None and expectedConverted is not None:
+                            print(f"{builtConverted} vs {expectedConverted}")
 
         if len(map_search_diff) >= diffCount and diffs > shift_cap:
             break
diff --git a/src/mapfile_parser/utils.py b/src/mapfile_parser/utils.py
index e4b3d6e..a71faac 100644
--- a/src/mapfile_parser/utils.py
+++ b/src/mapfile_parser/utils.py
@@ -26,7 +26,7 @@ def readFileAsBytearray(filepath: Path) -> bytearray:
     with filepath.open(mode="rb") as f:
         return bytearray(f.read())
 
-def hexbytes(bs):
+def hexbytes(bs: bytes) -> str:
     return ":".join("{:02X}".format(c) for c in bs)
 
 def getGitCommitTimestamp() -> int: