diff --git a/src/app.py b/src/app.py
index b9c9aac..1c02d89 100644
--- a/src/app.py
+++ b/src/app.py
@@ -2,6 +2,8 @@ import json
 import subprocess
 import typer
 from pathlib import Path
+import re
+import click
 
 from models.streams import VideoFile, VideoStream, AudioStream, SubtitleStream, OriginalMediaType
 from movie_details import get_movie_details
@@ -23,10 +25,19 @@ def parse_streams(stream_data: dict, VideoFile: VideoFile) -> VideoFile:
     return VideoFile
 
 
+def validate_imdb(ctx: click.Context, param: click.Parameter, value: str) -> str:
+    """Validate that an IMDb ID matches 'tt' followed by 7-8 digits."""
+    if value is None:
+        return value
+    if not re.match(r"^tt\d{7,8}$", value):
+        raise click.BadParameter("IMDb ID must be 'tt' followed by 7-8 digits (e.g. tt1234567)")
+    return value
+
+
 @app.command()
 def main(
     filename: Path = typer.Argument(..., exists=True, help="Input video file"),
-    imdb: str = typer.Option(None, "-i", "--imdb", help="IMDB ID"),
+    imdb: str = typer.Option(None, "-i", "--imdb", callback=validate_imdb, help="IMDB ID"),
     nosubtitles: bool = typer.Option(False, "-ns", "--nosubtitles", help="Remove subtitles"),
     preset: int = typer.Option(2, "-p", "--preset", help="Encoding preset"),
     crf: int = typer.Option(30, "-c", "--crf", help="CRF value"),