diff --git a/MarkItDown.spec b/MarkItDown.spec
index 3e100dc..613231d 100644
--- a/MarkItDown.spec
+++ b/MarkItDown.spec
@@ -1,42 +1,10 @@
 # -*- mode: python ; coding: utf-8 -*-
 import os
 from PyInstaller.utils.hooks import collect_data_files, collect_submodules
+from markitdowngui.build_config import build_datas, build_hiddenimports
 
-# Keep hidden imports minimal and focused on runtime-dynamic conversion modules.
-hiddenimports = [
-    "packaging.version",
-    "requests",
-]
-hiddenimports += collect_submodules("markitdown")
-for package in (
-    "azure.ai.documentintelligence",
-    "azure.identity",
-    "pypdfium2",
-    "pypdfium2_raw",
-    "pytesseract",
-):
-    try:
-        hiddenimports += collect_submodules(package)
-    except Exception as e:
-        print(f"Warning: Could not collect hidden imports for {package}: {e}")
-
-datas = [
-    ("markitdowngui/resources/markitdown-gui.ico", "markitdowngui/resources"),
-    ("markitdowngui/resources/moon.svg", "markitdowngui/resources"),
-    ("markitdowngui/resources/sun.svg", "markitdowngui/resources"),
-    ("LICENSE", "."),
-]
-
-try:
-    datas += collect_data_files("magika")
-except Exception as e:
-    print(f"Warning: Could not collect magika data files: {e}")
-
-for package in ("pypdfium2", "pypdfium2_raw"):
-    try:
-        datas += collect_data_files(package)
-    except Exception as e:
-        print(f"Warning: Could not collect data files for {package}: {e}")
+hiddenimports = build_hiddenimports(collect_submodules, warn=print)
+datas = build_datas(collect_data_files, warn=print)
 
 a = Analysis(
     ["markitdowngui/main.py"],
diff --git a/markitdowngui/build_config.py b/markitdowngui/build_config.py
new file mode 100644
index 0000000..4347271
--- /dev/null
+++ b/markitdowngui/build_config.py
@@ -0,0 +1,76 @@
+from __future__ import annotations
+
+from collections.abc import Callable
+
+BASE_HIDDENIMPORTS = (
+    "packaging.version",
+    "requests",
+    "charset_normalizer",
+    "charset_normalizer.md",
+    "charset_normalizer.md__mypyc",
+)
+MANDATORY_HIDDENIMPORT_PACKAGES = (
+    "markitdown",
+    "charset_normalizer",
+)
+OPTIONAL_HIDDENIMPORT_PACKAGES = (
+    "azure.ai.documentintelligence",
+    "azure.identity",
+    "pypdfium2",
+    "pypdfium2_raw",
+    "pytesseract",
+)
+BASE_DATAS = (
+    ("markitdowngui/resources/markitdown-gui.ico", "markitdowngui/resources"),
+    ("markitdowngui/resources/moon.svg", "markitdowngui/resources"),
+    ("markitdowngui/resources/sun.svg", "markitdowngui/resources"),
+    ("LICENSE", "."),
+)
+OPTIONAL_DATA_PACKAGES = (
+    "magika",
+    "pypdfium2",
+    "pypdfium2_raw",
+)
+
+
+def _dedupe(items: list[str]) -> list[str]:
+    return list(dict.fromkeys(items))
+
+
+def build_hiddenimports(
+    collect_submodules: Callable[[str], list[str]],
+    *,
+    warn: Callable[[str], None] | None = None,
+) -> list[str]:
+    hiddenimports = list(BASE_HIDDENIMPORTS)
+
+    for package in MANDATORY_HIDDENIMPORT_PACKAGES:
+        hiddenimports.extend(collect_submodules(package))
+
+    for package in OPTIONAL_HIDDENIMPORT_PACKAGES:
+        try:
+            hiddenimports.extend(collect_submodules(package))
+        except Exception as exc:
+            if warn is not None:
+                warn(
+                    f"Warning: Could not collect hidden imports for {package}: {exc}"
+                )
+
+    return _dedupe(hiddenimports)
+
+
+def build_datas(
+    collect_data_files: Callable[[str], list[tuple[str, str]]],
+    *,
+    warn: Callable[[str], None] | None = None,
+) -> list[tuple[str, str]]:
+    datas = list(BASE_DATAS)
+
+    for package in OPTIONAL_DATA_PACKAGES:
+        try:
+            datas.extend(collect_data_files(package))
+        except Exception as exc:
+            if warn is not None:
+                warn(f"Warning: Could not collect data files for {package}: {exc}")
+
+    return datas
diff --git a/tests/test_build_config.py b/tests/test_build_config.py
new file mode 100644
index 0000000..f4efc9d
--- /dev/null
+++ b/tests/test_build_config.py
@@ -0,0 +1,70 @@
+from markitdowngui import build_config
+
+
+def test_build_hiddenimports_includes_charset_normalizer_mypyc_runtime():
+    calls = []
+
+    def fake_collect(package: str) -> list[str]:
+        calls.append(package)
+        return {
+            "markitdown": ["markitdown._markdown"],
+            "charset_normalizer": ["charset_normalizer.api"],
+            "azure.ai.documentintelligence": ["azure.ai.documentintelligence._client"],
+            "azure.identity": [],
+            "pypdfium2": [],
+            "pypdfium2_raw": [],
+            "pytesseract": [],
+        }[package]
+
+    hiddenimports = build_config.build_hiddenimports(fake_collect)
+
+    assert "charset_normalizer" in hiddenimports
+    assert "charset_normalizer.md" in hiddenimports
+    assert "charset_normalizer.md__mypyc" in hiddenimports
+    assert "markitdown._markdown" in hiddenimports
+    assert calls[:2] == ["markitdown", "charset_normalizer"]
+
+
+def test_build_hiddenimports_warns_and_keeps_required_modules_when_optional_collection_fails():
+    warnings = []
+
+    def fake_collect(package: str) -> list[str]:
+        if package == "markitdown":
+            return []
+        if package == "charset_normalizer":
+            return []
+        if package == "pytesseract":
+            raise RuntimeError("missing optional package")
+        return []
+
+    hiddenimports = build_config.build_hiddenimports(
+        fake_collect,
+        warn=warnings.append,
+    )
+
+    assert "charset_normalizer.md__mypyc" in hiddenimports
+    assert warnings == [
+        "Warning: Could not collect hidden imports for pytesseract: missing optional package"
+    ]
+
+
+def test_build_datas_keeps_base_files_and_warns_for_missing_optional_packages():
+    warnings = []
+
+    def fake_collect(package: str) -> list[tuple[str, str]]:
+        if package == "magika":
+            return [("magika/model.onnx", "magika")]
+        if package == "pypdfium2":
+            raise RuntimeError("missing pdf runtime")
+        if package == "pypdfium2_raw":
+            return [("pdfium.dll", "pypdfium2_raw")]
+        raise AssertionError(f"Unexpected package: {package}")
+
+    datas = build_config.build_datas(fake_collect, warn=warnings.append)
+
+    assert ("LICENSE", ".") in datas
+    assert ("magika/model.onnx", "magika") in datas
+    assert ("pdfium.dll", "pypdfium2_raw") in datas
+    assert warnings == [
+        "Warning: Could not collect data files for pypdfium2: missing pdf runtime"
+    ]