diff --git a/src/repository/api/ArcanistSubversionAPI.php b/src/repository/api/ArcanistSubversionAPI.php
--- a/src/repository/api/ArcanistSubversionAPI.php
+++ b/src/repository/api/ArcanistSubversionAPI.php
@@ -40,6 +40,16 @@
     $argv[0] = 'svn '.$argv[0];
 
     $future = newv('ExecFuture', $argv);
+
+    // For historical reasons we run Subversion commands keeping env.
+    // But, let's keep English, to have a reliable parser.
+    // https://github.com/apache/subversion/blob/trunk/notes/l10n-problems
+    // https://www.gnu.org/software/gettext/manual/gettext.html
+    // https://svnbook.red-bean.com/en/1.7/svn.advanced.l10n.html
+    // https://superuser.com/a/1779369/390314
+    $future->updateEnv('LC_ALL', 'C'); // designed for scripts, override LC_*
+    $future->updateEnv('LANG', 'C'); // deactivate LANGUAGE, defuse LC defaults
+
     $future->setCWD($this->getPath());
     return $future;
   }