diff --git a/server/scripts/install_tcm_ancient_books.php b/server/scripts/install_tcm_ancient_books.php
index 073f13053..4eed80678 100644
--- a/server/scripts/install_tcm_ancient_books.php
+++ b/server/scripts/install_tcm_ancient_books.php
@@ -18,37 +18,47 @@ $root = dirname(__DIR__) . '/knowledge/tcm-ancient-books';
 $projectRoot = dirname(__DIR__, 2);
 $indexPath = TcmAncientBooksReference::indexPath();
 
-function runGit(array $arguments): string
+function runGit(array $arguments, ?string $directory = null): string
 {
-    $command = 'git ' . implode(' ', array_map('escapeshellarg', $arguments)) . ' 2>&1';
-    $lines = [];
-    $code = 0;
-    exec($command, $lines, $code);
-    if ($code !== 0) {
-        throw new RuntimeException('Git command failed: ' . implode("\n", $lines));
+    $originalDirectory = getcwd();
+    if ($directory !== null && ($originalDirectory === false || !chdir($directory))) {
+        throw new RuntimeException('Could not enter Git directory: ' . $directory);
+    }
+    try {
+        $command = 'git ' . implode(' ', array_map('escapeshellarg', $arguments)) . ' 2>&1';
+        $lines = [];
+        $code = 0;
+        exec($command, $lines, $code);
+        if ($code !== 0) {
+            throw new RuntimeException('Git command failed: ' . implode("\n", $lines));
+        }
+        return trim(implode("\n", $lines));
+    } finally {
+        if ($directory !== null) {
+            chdir($originalDirectory);
+        }
     }
-    return trim(implode("\n", $lines));
 }
 
 try {
     if (!is_dir($root . '/.git') && !is_file($root . '/.git')) {
         if (is_file($projectRoot . '/.gitmodules')
             && (is_dir($projectRoot . '/.git') || is_file($projectRoot . '/.git'))) {
-            runGit(['-C', $projectRoot, 'submodule', 'update', '--init', '--', 'server/knowledge/tcm-ancient-books']);
+            runGit(['submodule', 'update', '--init', '--', 'server/knowledge/tcm-ancient-books'], $projectRoot);
         } else {
             runGit(['clone', '--depth', '1', TcmAncientBooksReference::REPOSITORY_URL . '.git', $root]);
         }
     }
-    $checkoutRoot = runGit(['-C', $root, 'rev-parse', '--show-toplevel']);
+    $checkoutRoot = runGit(['rev-parse', '--show-toplevel'], $root);
     if (strtolower(str_replace('\\', '/', (string) realpath($checkoutRoot)))
         !== strtolower(str_replace('\\', '/', (string) realpath($root)))) {
         throw new RuntimeException('Corpus checkout is missing or points to the parent repository');
     }
-    $head = runGit(['-C', $root, 'rev-parse', 'HEAD']);
+    $head = runGit(['rev-parse', 'HEAD'], $root);
     if ($head !== TcmAncientBooksReference::COMMIT) {
-        runGit(['-C', $root, 'fetch', '--depth', '1', 'origin', TcmAncientBooksReference::COMMIT]);
-        runGit(['-C', $root, 'checkout', '--detach', TcmAncientBooksReference::COMMIT]);
-        $head = runGit(['-C', $root, 'rev-parse', 'HEAD']);
+        runGit(['fetch', '--depth', '1', 'origin', TcmAncientBooksReference::COMMIT], $root);
+        runGit(['checkout', '--detach', TcmAncientBooksReference::COMMIT], $root);
+        $head = runGit(['rev-parse', 'HEAD'], $root);
     }
     if ($head !== TcmAncientBooksReference::COMMIT) {
         throw new RuntimeException('Corpus commit mismatch');