diff --git a/scripts/linux-binaries-manifest.test.mjs b/scripts/linux-binaries-manifest.test.mjs
index bf66fc342f..be980d0e7c 100644
--- a/scripts/linux-binaries-manifest.test.mjs
+++ b/scripts/linux-binaries-manifest.test.mjs
@@ -451,6 +451,34 @@ test('the mirror keeps only the two newest versions and skips an unchanged lates
   assert.doesNotMatch(syncScript, /! -name '0\.2\.\*'/);
 });
 
+test('pruning keeps the two newest SemVer releases and drops a newer-looking beta', () => {
+  const temp = fs.mkdtempSync(path.join(os.tmpdir(), 'openbitfun-prune-'));
+  for (const name of ['0.2.19', '1.0.0-beta', '1.0.0', '1.0.1']) {
+    fs.mkdirSync(path.join(temp, name));
+  }
+  const result = spawnSync(
+    'bash',
+    ['-c', `
+      source "$SYNC_SCRIPT"
+      WEBSITE_RELEASE_DIR="$TEST_DIR"
+      KEEP_VERSIONS=2
+      PYTHON=python3
+      prune_old_versions
+    `],
+    {
+      encoding: 'utf8',
+      env: {
+        ...process.env,
+        SYNC_SCRIPT: path.join(repoRoot, 'scripts/openbitfun-release-sync.sh'),
+        TEST_DIR: temp,
+      },
+    }
+  );
+  assert.equal(result.status, 0, result.stderr);
+  assert.deepEqual(fs.readdirSync(temp).sort(), ['1.0.0', '1.0.1']);
+  fs.rmSync(temp, { recursive: true, force: true });
+});
+
 test('openbitfun sync lock and cron use the in-repo script, not a server-only copy', () => {
   const syncScript = fs.readFileSync(
     path.join(repoRoot, 'scripts/openbitfun-release-sync.sh'),
diff --git a/scripts/openbitfun-release-sync.sh b/scripts/openbitfun-release-sync.sh
index 8f1866268c..4ff569e177 100755
--- a/scripts/openbitfun-release-sync.sh
+++ b/scripts/openbitfun-release-sync.sh
@@ -683,7 +683,22 @@ prune_old_versions() {
   local dirs=() total remove_count i
   while IFS= read -r d; do
     dirs+=("$d")
-  done < <(find "$WEBSITE_RELEASE_DIR" -mindepth 1 -maxdepth 1 -type d | sort -V)
+  done < <("$PYTHON" - "$WEBSITE_RELEASE_DIR" <<'PY'
+import os, re, sys
+root = sys.argv[1]
+names = [name for name in os.listdir(root) if os.path.isdir(os.path.join(root, name))]
+
+def key(name):
+    match = re.fullmatch(r"(\d+)\.(\d+)\.(\d+)(?:-(.+))?", name)
+    if not match:
+        return (0, 0, 0, 0, name)
+    pre = match.group(4)
+    return (int(match.group(1)), int(match.group(2)), int(match.group(3)), 1 if pre is None else 0, pre or "")
+
+for name in sorted(names, key=key):
+    print(os.path.join(root, name))
+PY
+)
   total=${#dirs[@]}
   if [ "$total" -le "$KEEP_VERSIONS" ]; then
     return 0