diff --git a/emulators/ares.yml b/emulators/ares.yml
index 6362bf7f..72ed6c9f 100644
--- a/emulators/ares.yml
+++ b/emulators/ares.yml
@@ -11,6 +11,7 @@ mode: standalone
 systems:
   - arcade
   - atari-2600
+  - atari-5200
   - colecovision
   - myvision
   - famicom
@@ -51,7 +52,8 @@ systems:
 
 notes: |
   Multi-system emulator by Near (byuu), successor to higan/bsnes. Focuses on
-  accuracy and preservation. 38 systems emulated.
+  accuracy and preservation. 41 emulators registered at this pin
+  (desktop-ui/emulator/emulators.cpp).
 
   Firmware identification uses SHA256 hashes. Filenames are user-defined; ares
   scans a configured directory and matches by hash. EmuDeck installs ares as
@@ -89,6 +91,16 @@ notes: |
   SuperGrafx, SG-1000, SC-3000.
 
 files:
+  # --- Atari 5200 ---
+  - name: 5200.rom
+    system: atari-5200
+    required: true
+    size: 2048
+    sha256: "06b250f18983d058c0f156ce7ee88ae48b6eaf11e6f10f21dccf6ac7ffb6a6af"
+    validation: [size, sha256]
+    description: "Atari 5200 BIOS (NTSC-U four-port)"
+    source_ref: "desktop-ui/emulator/atari-5200.cpp:12-16, desktop-ui/emulator/atari-5200.cpp:82-88, mia/system/atari-5200.cpp:7-10"
+
   # --- ColecoVision ---
   - name: colecovision.rom
     system: colecovision
diff --git a/tests/test_profile_checks.py b/tests/test_profile_checks.py
index b74e3787..b38c0ce4 100644
--- a/tests/test_profile_checks.py
+++ b/tests/test_profile_checks.py
@@ -132,5 +132,21 @@ class Atari800SystemRoms(_Probe):
                 self.assertFalse(self.accepts("atari800", name, b"\1" * size))
 
 
+class AresAtari5200Bios(unittest.TestCase):
+    """ares registers an Atari 5200 firmware by sha256 and refuses to load a
+    game without it (desktop-ui/emulator/atari-5200.cpp:12-16, 82-88 at
+    4cb8d92); the profile left the system out, so no pack carried the BIOS."""
+
+    def test_the_profile_declares_it(self):
+        profile = _profile("ares")
+        self.assertIn("atari-5200", profile["systems"])
+        entry = next(f for f in profile["files"] if f.get("system") == "atari-5200")
+        self.assertTrue(entry["required"])
+        self.assertEqual(
+            entry["sha256"],
+            "06b250f18983d058c0f156ce7ee88ae48b6eaf11e6f10f21dccf6ac7ffb6a6af",
+        )
+
+
 if __name__ == "__main__":
     unittest.main()