diff --git a/install.ps1 b/install.ps1
index d321dfe7b..19035cf81 100644
--- a/install.ps1
+++ b/install.ps1
@@ -16,7 +16,7 @@
     # and Invoke-WebRequest throws on a cut transfer before the hash is read:
     # the site's build rewrites this line there (scripts/sitebootstrap.py).
     $mismatchAdvice = "The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-    $defaultInstallSha256 = "f0410caadbcc354efc86038decb95da63478ddf018cad03ec09e41ce2b5e4d63"
+    $defaultInstallSha256 = "0aacd5847f927fe058de40f34f09ba4676acafe9d3e3d6c4228e46a474ed8744"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }
diff --git a/install.py b/install.py
index 318048d69..e9d697b78 100644
--- a/install.py
+++ b/install.py
@@ -138,8 +138,10 @@ OMISSION_REASONS = {
 # says, and as the installer words it. Firmware carries no category.
 GAME_DATA = "game_data"
 CATEGORY_LABELS = {GAME_DATA: "game data"}
-_SHA1_RE = re.compile(r"^[0-9a-fA-F]{40}$")
-_SHA256_RE = re.compile(r"^[0-9a-fA-F]{64}$")
+# The manifest writes its digests in lowercase, as hashlib gives them, and
+# every comparison reads them as written.
+_SHA1_RE = re.compile(r"^[0-9a-f]{40}$")
+_SHA256_RE = re.compile(r"^[0-9a-f]{64}$")
 
 # The region vocabulary of scripts/region.py, which this file cannot import.
 # A test holds the two copies equal.
@@ -3592,9 +3594,6 @@ def _check_entry(
     return size, largest
 
 
-_SHA1_RE = re.compile(r"^[0-9a-f]{40}$")
-
-
 def _check_data_directory(entry: object, where: str) -> None:
     """A data directory: its source archive, its mapping, its file list."""
     if not isinstance(entry, dict):
@@ -3631,7 +3630,7 @@ def _check_data_directory(entry: object, where: str) -> None:
         if (
             not isinstance(meta, dict)
             or not isinstance(meta.get("sha1"), str)
-            or not _SHA1_RE.match(meta["sha1"])
+            or not _SHA1_RE.fullmatch(meta["sha1"])
             or not isinstance(meta.get("size"), int)
             or not 0 <= meta["size"] <= MAX_DOWNLOAD_SIZE
         ):
diff --git a/install.sh b/install.sh
index ebf1fc626..d5eaaea86 100755
--- a/install.sh
+++ b/install.sh
@@ -23,7 +23,7 @@ DEFAULT_INSTALL_URL="https://raw.githubusercontent.com/Abdess/retrobios/main/ins
 # curl or wget stop on a cut transfer before the hash is read: the site's
 # build rewrites this line there (scripts/sitebootstrap.py).
 MISMATCH_ADVICE="The download was most likely cut short: try again. Within minutes of an update of this project the two files can come from caches of different ages. Waiting five minutes settles that."
-DEFAULT_INSTALL_SHA256="f0410caadbcc354efc86038decb95da63478ddf018cad03ec09e41ce2b5e4d63"
+DEFAULT_INSTALL_SHA256="0aacd5847f927fe058de40f34f09ba4676acafe9d3e3d6c4228e46a474ed8744"
 MAX_INSTALLER_BYTES=2097152
 
 cleanup() {
diff --git a/install/launchers/index.json b/install/launchers/index.json
index 5e538378d..300728f9c 100644
--- a/install/launchers/index.json
+++ b/install/launchers/index.json
@@ -27,8 +27,8 @@
         {
           "dest": "roms/ports/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1089187,
-          "sha256": "f0410caadbcc354efc86038decb95da63478ddf018cad03ec09e41ce2b5e4d63",
+          "size": 1089259,
+          "sha256": "0aacd5847f927fe058de40f34f09ba4676acafe9d3e3d6c4228e46a474ed8744",
           "executable": false
         },
         {
@@ -71,8 +71,8 @@
     "muos": {
       "archive": {
         "dest": "ARCHIVE/RetroBIOS.muxapp",
-        "size": 1142814,
-        "sha256": "090c40f23a9c087641c9835a79a0d4181fc702865ce20e5115fe5a7ca72a31fc"
+        "size": 1142886,
+        "sha256": "4068768b8a88f1caa5238a8f9b5f0a0a34c1a6acab3577b54075c4163ca37ca6"
       },
       "members": [
         {
@@ -92,8 +92,8 @@
         {
           "name": "RetroBIOS/install.py",
           "repo_path": "install.py",
-          "size": 1089187,
-          "sha256": "f0410caadbcc354efc86038decb95da63478ddf018cad03ec09e41ce2b5e4d63",
+          "size": 1089259,
+          "sha256": "0aacd5847f927fe058de40f34f09ba4676acafe9d3e3d6c4228e46a474ed8744",
           "executable": false
         },
         {
@@ -166,8 +166,8 @@
         {
           "dest": ".config/modules/retrobios/install.py",
           "repo_path": "install.py",
-          "size": 1089187,
-          "sha256": "f0410caadbcc354efc86038decb95da63478ddf018cad03ec09e41ce2b5e4d63",
+          "size": 1089259,
+          "sha256": "0aacd5847f927fe058de40f34f09ba4676acafe9d3e3d6c4228e46a474ed8744",
           "executable": false
         },
         {
diff --git a/tests/test_install_cores.py b/tests/test_install_cores.py
index 9c58ba3a5..55fcbfbf0 100644
--- a/tests/test_install_cores.py
+++ b/tests/test_install_cores.py
@@ -192,6 +192,29 @@ class TheBoundaryBoundsAlternatives(unittest.TestCase):
             install._validate_manifest(manifest, "retroarch")
 
 
+class OneDigestRuleAtTheBoundary(unittest.TestCase):
+    """install.py defined _SHA1_RE twice: the second, lowercase only,
+    replaced the first everywhere, so an uppercase sha1 was refused where
+    an uppercase sha256 passed. Every comparison reads the digest as
+    hashlib writes it, so both refuse uppercase, data trees included."""
+
+    def _manifest(self, **digests: str) -> dict:
+        entry = {"dest": "a.bin", "size": 1, "repo_path": "bios/a.bin", **digests}
+        return {"manifest_version": 2, "platform": "retroarch", "files": [entry]}
+
+    def test_sha1_and_sha256_follow_the_same_rule(self):
+        install._validate_manifest(self._manifest(sha1="a" * 40), "retroarch")
+        install._validate_manifest(self._manifest(sha256="a" * 64), "retroarch")
+        for digests in ({"sha1": "A" * 40}, {"sha256": "A" * 64}):
+            with self.subTest(digests=digests), self.assertRaises(ValueError):
+                install._validate_manifest(self._manifest(**digests), "retroarch")
+
+    def test_one_definition_each(self):
+        source = (REPO_ROOT / "install.py").read_text(encoding="utf-8")
+        for name in ("_SHA1_RE", "_SHA256_RE"):
+            self.assertEqual(source.count(f"\n{name} = "), 1, name)
+
+
 class APlatformOmissionKeepsItsClaim(unittest.TestCase):
     """A file the platform declares and a core reads, absent from the
     collection, was recorded under the core alone: RetroPie's dsi_nand.bin