diff --git a/dist/renamer-0.8.11-py3-none-any.whl b/dist/renamer-0.8.11-py3-none-any.whl
new file mode 100644
index 0000000..2b6ff24
Binary files /dev/null and b/dist/renamer-0.8.11-py3-none-any.whl differ
diff --git a/pyproject.toml b/pyproject.toml
index dd26383..24824a2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "renamer"
-version = "0.8.10"
+version = "0.8.11"
 description = "Terminal-based media file renamer and metadata viewer"
 readme = "README.md"
 requires-python = ">=3.11"
diff --git a/renamer/constants/__init__.py b/renamer/constants/__init__.py
index e06d8bd..5623817 100644
--- a/renamer/constants/__init__.py
+++ b/renamer/constants/__init__.py
@@ -12,7 +12,11 @@ This package contains constants split into logical modules:
 """
 
 # Import from all constant modules
-from .media_constants import MEDIA_TYPES, META_TYPE_TO_EXTENSIONS
+from .media_constants import (
+    MEDIA_TYPES,
+    META_TYPE_TO_EXTENSIONS,
+    get_extension_from_format
+)
 from .source_constants import SOURCE_DICT
 from .frame_constants import FRAME_CLASSES, NON_STANDARD_QUALITY_INDICATORS
 from .moviedb_constants import MOVIE_DB_DICT
@@ -25,6 +29,7 @@ __all__ = [
     # Media types
     'MEDIA_TYPES',
     'META_TYPE_TO_EXTENSIONS',
+    'get_extension_from_format',
     # Source types
     'SOURCE_DICT',
     # Frame classes
diff --git a/renamer/constants/media_constants.py b/renamer/constants/media_constants.py
index 830ba05..99d9908 100644
--- a/renamer/constants/media_constants.py
+++ b/renamer/constants/media_constants.py
@@ -1,6 +1,7 @@
 """Media type constants for supported video formats.
 
 This module defines all supported video container formats and their metadata.
+Each entry includes the MediaInfo format name for proper detection.
 """
 
 MEDIA_TYPES = {
@@ -8,50 +9,79 @@ MEDIA_TYPES = {
         "description": "Matroska multimedia container",
         "meta_type": "Matroska",
         "mime": "video/x-matroska",
+        "mediainfo_format": "Matroska",
     },
     "mk3d": {
         "description": "Matroska 3D multimedia container",
         "meta_type": "Matroska",
         "mime": "video/x-matroska",
+        "mediainfo_format": "Matroska",
     },
     "avi": {
         "description": "Audio Video Interleave",
         "meta_type": "AVI",
         "mime": "video/x-msvideo",
+        "mediainfo_format": "AVI",
     },
     "mov": {
         "description": "QuickTime movie",
         "meta_type": "QuickTime",
         "mime": "video/quicktime",
+        "mediainfo_format": "QuickTime",
     },
     "mp4": {
         "description": "MPEG-4 video container",
         "meta_type": "MP4",
         "mime": "video/mp4",
+        "mediainfo_format": "MPEG-4",
     },
     "wmv": {
         "description": "Windows Media Video",
         "meta_type": "ASF",
         "mime": "video/x-ms-wmv",
+        "mediainfo_format": "Windows Media",
+    },
+    "flv": {
+        "description": "Flash Video",
+        "meta_type": "FLV",
+        "mime": "video/x-flv",
+        "mediainfo_format": "Flash Video",
     },
-    "flv": {"description": "Flash Video", "meta_type": "FLV", "mime": "video/x-flv"},
     "webm": {
         "description": "WebM multimedia",
         "meta_type": "WebM",
         "mime": "video/webm",
+        "mediainfo_format": "WebM",
+    },
+    "m4v": {
+        "description": "MPEG-4 video",
+        "meta_type": "MP4",
+        "mime": "video/mp4",
+        "mediainfo_format": "MPEG-4",
+    },
+    "3gp": {
+        "description": "3GPP multimedia",
+        "meta_type": "MP4",
+        "mime": "video/3gpp",
+        "mediainfo_format": "MPEG-4",
+    },
+    "ogv": {
+        "description": "Ogg Video",
+        "meta_type": "Ogg",
+        "mime": "video/ogg",
+        "mediainfo_format": "Ogg",
     },
-    "m4v": {"description": "MPEG-4 video", "meta_type": "MP4", "mime": "video/mp4"},
-    "3gp": {"description": "3GPP multimedia", "meta_type": "MP4", "mime": "video/3gpp"},
-    "ogv": {"description": "Ogg Video", "meta_type": "Ogg", "mime": "video/ogg"},
     "mpg": {
         "description": "MPEG video",
         "meta_type": "MPEG-PS",
         "mime": "video/mpeg",
+        "mediainfo_format": "MPEG-PS",
     },
     "mpeg": {
         "description": "MPEG video",
         "meta_type": "MPEG-PS",
         "mime": "video/mpeg",
+        "mediainfo_format": "MPEG-PS",
     },
 }
 
@@ -64,3 +94,31 @@ for ext, info in MEDIA_TYPES.items():
         if meta_type not in META_TYPE_TO_EXTENSIONS:
             META_TYPE_TO_EXTENSIONS[meta_type] = []
         META_TYPE_TO_EXTENSIONS[meta_type].append(ext)
+
+# Reverse mapping: MediaInfo format name -> extension
+# Built from MEDIA_TYPES at module load
+MEDIAINFO_FORMAT_TO_EXTENSION = {}
+for ext, info in MEDIA_TYPES.items():
+    mediainfo_format = info.get('mediainfo_format')
+    if mediainfo_format:
+        # Store only the first (primary) extension for each format
+        if mediainfo_format not in MEDIAINFO_FORMAT_TO_EXTENSION:
+            MEDIAINFO_FORMAT_TO_EXTENSION[mediainfo_format] = ext
+
+
+def get_extension_from_format(format_name: str) -> str | None:
+    """Get file extension from MediaInfo format name.
+
+    Args:
+        format_name: Format name as reported by MediaInfo (e.g., "MPEG-4", "Matroska")
+
+    Returns:
+        File extension (e.g., "mp4", "mkv") or None if format is unknown
+
+    Example:
+        >>> get_extension_from_format("MPEG-4")
+        'mp4'
+        >>> get_extension_from_format("Matroska")
+        'mkv'
+    """
+    return MEDIAINFO_FORMAT_TO_EXTENSION.get(format_name)
diff --git a/renamer/extractors/default_extractor.py b/renamer/extractors/default_extractor.py
index e717fca..1887a68 100644
--- a/renamer/extractors/default_extractor.py
+++ b/renamer/extractors/default_extractor.py
@@ -101,7 +101,7 @@ class DefaultExtractor:
         return None
 
     def extract_extension(self) -> Optional[str]:
-        """Return file extension. Returns None as no extension is available."""
+        """Return file extension. Returns 'ext' as default placeholder."""
         return "ext"
 
     def extract_tmdb_url(self) -> Optional[str]:
diff --git a/renamer/extractors/fileinfo_extractor.py b/renamer/extractors/fileinfo_extractor.py
index 4faf801..fcdf7f3 100644
--- a/renamer/extractors/fileinfo_extractor.py
+++ b/renamer/extractors/fileinfo_extractor.py
@@ -83,10 +83,12 @@ class FileInfoExtractor:
         return str(self._file_path)
 
     @cached_method()
-    def extract_extension(self) -> str:
+    def extract_extension(self) -> str | None:
         """Extract file extension without the dot.
 
         Returns:
-            File extension in lowercase without leading dot (e.g., "mkv", "mp4")
+            File extension in lowercase without leading dot (e.g., "mkv", "mp4"),
+            or None if no extension exists
         """
-        return self._file_path.suffix.lower().lstrip('.')
\ No newline at end of file
+        ext = self._file_path.suffix.lower().lstrip('.')
+        return ext if ext else None
\ No newline at end of file
diff --git a/renamer/extractors/mediainfo_extractor.py b/renamer/extractors/mediainfo_extractor.py
index d1d0a65..32bef90 100644
--- a/renamer/extractors/mediainfo_extractor.py
+++ b/renamer/extractors/mediainfo_extractor.py
@@ -1,7 +1,7 @@
 from pathlib import Path
 from pymediainfo import MediaInfo
 from collections import Counter
-from ..constants import FRAME_CLASSES, META_TYPE_TO_EXTENSIONS
+from ..constants import FRAME_CLASSES, get_extension_from_format
 from ..cache import cached_method, Cache
 import langcodes
 import logging
@@ -265,23 +265,31 @@ class MediaInfoExtractor:
 
     @cached_method()
     def extract_extension(self) -> str | None:
-        """Extract file extension based on container format"""
+        """Extract file extension based on container format.
+
+        Uses MediaInfo's format field to determine the appropriate file extension.
+        Handles special cases like Matroska 3D (mk3d vs mkv).
+
+        Returns:
+            File extension (e.g., "mp4", "mkv") or None if format is unknown
+        """
         if not self.media_info:
             return None
         general_track = next((t for t in self.media_info.tracks if t.track_type == 'General'), None)
         if not general_track:
             return None
         format_ = getattr(general_track, 'format', None)
-        if format_ in META_TYPE_TO_EXTENSIONS:
-            exts = META_TYPE_TO_EXTENSIONS[format_]
-            if format_ == 'Matroska':
-                if self.is_3d() and 'mk3d' in exts:
-                    return 'mk3d'
-                else:
-                    return 'mkv'
-            else:
-                return exts[0] if exts else None
-        return None
+        if not format_:
+            return None
+
+        # Use the constants function to get extension from format
+        ext = get_extension_from_format(format_)
+
+        # Special case: Matroska 3D uses mk3d extension
+        if ext == 'mkv' and self.is_3d():
+            return 'mk3d'
+
+        return ext
 
     @cached_method()
     def extract_3d_layout(self) -> str | None:
diff --git a/uv.lock b/uv.lock
index e2fa171..17cc825 100644
--- a/uv.lock
+++ b/uv.lock
@@ -462,7 +462,7 @@ wheels = [
 
 [[package]]
 name = "renamer"
-version = "0.8.10"
+version = "0.8.11"
 source = { editable = "." }
 dependencies = [
     { name = "langcodes" },