diff --git a/homeassistant/components/media_source/__init__.py b/homeassistant/components/media_source/__init__.py
index 2f996523fdc..928e46ab528 100644
--- a/homeassistant/components/media_source/__init__.py
+++ b/homeassistant/components/media_source/__init__.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from collections.abc import Callable
-from typing import Any
+from typing import Any, Protocol
 
 import voluptuous as vol
 
@@ -58,6 +58,13 @@ __all__ = [
 CONFIG_SCHEMA = cv.empty_config_schema(DOMAIN)
 
 
+class MediaSourceProtocol(Protocol):
+    """Define the format of media_source platforms."""
+
+    async def async_get_media_source(self, hass: HomeAssistant) -> MediaSource:
+        """Set up media source."""
+
+
 def is_media_source_id(media_content_id: str) -> bool:
     """Test if identifier is a media source."""
     return URI_SCHEME_REGEX.match(media_content_id) is not None
@@ -87,7 +94,9 @@ async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
 
 
 async def _process_media_source_platform(
-    hass: HomeAssistant, domain: str, platform: Any
+    hass: HomeAssistant,
+    domain: str,
+    platform: MediaSourceProtocol,
 ) -> None:
     """Process a media source platform."""
     hass.data[DOMAIN][domain] = await platform.async_get_media_source(hass)