diff --git a/install.ps1 b/install.ps1
index dc2e8869..2a57af8b 100644
--- a/install.ps1
+++ b/install.ps1
@@ -8,7 +8,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-$defaultInstallSha256 = "431f7d05350e222a3f4746dd13116bf570ec0f80117eed47d747372c61b57d77"
+$defaultInstallSha256 = "dc6b428278a4352923c19ddcf055fd994aac1df77f35cb1d097e8f4c5d887ae1"
 $maximumInstallerBytes = 2MB
 $installerExit = 0
 $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index 78611275..7dacd8aa 100644
--- a/install.py
+++ b/install.py
@@ -870,6 +870,47 @@ def detect_frontends(os_type: str, home: Path | None = None) -> list[str]:
     return frontends
 
 
+# The registry's path_exists rules (platforms/_registry.yml install.detect),
+# one row each: (os, platform, path, BIOS directory when it is not the path).
+# The manifests publish them too, but detection runs before any manifest is
+# fetched; a test holds this table equal to the registry. Without it a Linux
+# home holding RetroPie/BIOS or .config/BizHawk/Firmware detected nothing.
+_PATH_RULES: tuple[tuple[str, str, str, str | None], ...] = (
+    ("windows", "retrobat", "C:\\RetroBat\\bios", None),
+    ("windows", "retrobat", "%USERPROFILE%\\RetroBat\\bios", None),
+    ("linux", "emudeck", "$HOME/Emulation/bios", None),
+    ("linux", "retrodeck", "$HOME/.var/app/net.retrodeck.retrodeck", "$HOME/retrodeck"),
+    ("linux", "romm", "/romm/library/bios", None),
+    ("linux", "retropie", "$HOME/RetroPie/BIOS", None),
+    ("windows", "bizhawk", "%USERPROFILE%\\BizHawk\\Firmware", None),
+    ("linux", "bizhawk", "$HOME/.config/BizHawk/Firmware", None),
+    ("linux", "misterfpga", "/media/fat/MiSTer", "/media/fat/games"),
+)
+
+
+def _rule_path(template: str) -> Path:
+    """A rule's path on this machine: $HOME or %USERPROFILE%, then the rest."""
+    bases = (
+        ("$HOME", Path.home()),
+        ("%USERPROFILE%", Path(os.environ.get("USERPROFILE") or Path.home())),
+    )
+    for variable, base in bases:
+        if template.startswith(variable):
+            rest = [part for part in re.split(r"[\\/]", template[len(variable):]) if part]
+            return base.joinpath(*rest)
+    return Path(template)
+
+
+def _detect_by_path(os_type: str, found: list[tuple[str, Path]]) -> None:
+    """Add what a registry path rule finds, for a platform not found yet."""
+    systems = ("linux", "windows") if os_type == "wsl" else (os_type,)
+    for rule_os, platform, path, bios in _PATH_RULES:
+        if rule_os not in systems or any(name == platform for name, _ in found):
+            continue
+        if _rule_path(path).exists():
+            found.append((platform, _rule_path(bios or path)))
+
+
 def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
     """Detect installed emulator platforms and their BIOS directories."""
     found: list[tuple[str, Path]] = []
@@ -981,6 +1022,7 @@ def detect_platforms(os_type: str) -> list[tuple[str, Path]]:
             if system_dir:
                 found.append(("retroarch", system_dir))
 
+    _detect_by_path(os_type, found)
     return found
 
 
diff --git a/install.sh b/install.sh
index 1715734c..097e4551 100755
--- a/install.sh
+++ b/install.sh
@@ -18,7 +18,7 @@ esac
 TEMP_INSTALLER=""
 TEMP_DIRECTORY=""
 DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-DEFAULT_INSTALL_SHA256="431f7d05350e222a3f4746dd13116bf570ec0f80117eed47d747372c61b57d77"
+DEFAULT_INSTALL_SHA256="dc6b428278a4352923c19ddcf055fd994aac1df77f35cb1d097e8f4c5d887ae1"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/tests/test_install.py b/tests/test_install.py
index 1d7f354f..f5caf519 100644
--- a/tests/test_install.py
+++ b/tests/test_install.py
@@ -920,6 +920,56 @@ class StandaloneCopiesReadWhereThePackPutTheFile(unittest.TestCase):
             install._validate_manifest(manifest, "emudeck")
 
 
+class DetectionFollowsTheRegistry(unittest.TestCase):
+    """The registry declared RetroPie at ~/RetroPie/BIOS and BizHawk at
+    ~/.config/BizHawk/Firmware, every manifest published it, and the
+    installer never read it: such a home detected nothing."""
+
+    def test_the_table_is_the_registry(self):
+        import yaml  # noqa: PLC0415
+
+        registry = yaml.safe_load(
+            (Path(__file__).resolve().parents[1] / "platforms" / "_registry.yml").read_text()
+        )
+        rules = {
+            (rule["os"], name, rule["path"], rule.get("bios_path"))
+            for name, entry in registry["platforms"].items()
+            for rule in (entry.get("install") or {}).get("detect", [])
+            if rule["method"] == "path_exists"
+        }
+        self.assertEqual(set(install._PATH_RULES), rules)
+
+    def _home(self) -> Path:
+        home = Path(_tempdir(self))
+        patcher = unittest.mock.patch.dict(os.environ, {"HOME": str(home), "USERPROFILE": str(home)})
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        return home
+
+    def test_a_home_layout_is_detected(self):
+        home = self._home()
+        (home / "RetroPie" / "BIOS").mkdir(parents=True)
+        (home / ".config" / "BizHawk" / "Firmware").mkdir(parents=True)
+        found: list = []
+        install._detect_by_path("linux", found)
+        self.assertIn(("retropie", home / "RetroPie" / "BIOS"), found)
+        self.assertIn(("bizhawk", home / ".config" / "BizHawk" / "Firmware"), found)
+
+    def test_a_windows_profile_path_is_detected(self):
+        home = self._home()
+        (home / "BizHawk" / "Firmware").mkdir(parents=True)
+        found: list = []
+        install._detect_by_path("windows", found)
+        self.assertEqual(found, [("bizhawk", home / "BizHawk" / "Firmware")])
+
+    def test_a_platform_already_found_is_not_added_again(self):
+        home = self._home()
+        (home / "Emulation" / "bios").mkdir(parents=True)
+        found = [("emudeck", home / "elsewhere" / "bios")]
+        install._detect_by_path("linux", found)
+        self.assertEqual(found, [("emudeck", home / "elsewhere" / "bios")])
+
+
 class InstallerStaysOnPython38AndTheStdlib(unittest.TestCase):
     """install.py runs where the bootstraps let it run: Python 3.8, stdlib only.