diff --git a/src/git-clone.ts b/src/git-clone.ts
index b9cd3708..ef3380e8 100644
--- a/src/git-clone.ts
+++ b/src/git-clone.ts
@@ -495,6 +495,10 @@ export function gitNonInteractiveEnv(base: NodeJS.ProcessEnv = process.env): Nod
     SSH_ASKPASS_REQUIRE: 'never',
     DISPLAY: '',
     GCM_INTERACTIVE: 'never',
+    // classifyGitFailure() matches git's ENGLISH stderr; a German or French locale would
+    // turn a missing ref into a generic FAILED (422 instead of 400).
+    LC_ALL: 'C',
+    LANG: 'C',
     GIT_SSH_COMMAND:
       base.GIT_SSH_COMMAND || 'ssh -oBatchMode=yes -oStrictHostKeyChecking=accept-new -oConnectTimeout=10',
   };
diff --git a/test/custom-model-run-menu-ui.test.ts b/test/custom-model-run-menu-ui.test.ts
index d1832113..336b9c5d 100644
--- a/test/custom-model-run-menu-ui.test.ts
+++ b/test/custom-model-run-menu-ui.test.ts
@@ -1342,8 +1342,8 @@ describe('Custom Model Endpoint Profiles: _confirmContextWarning (in-app modal,
     expect(modal.classList.contains('active')).toBe(true);
     const message = win.document.getElementById('customModelContextWarningMessage')!.textContent!;
     expect(message).toContain('qwen3.8-27b-ud-q4_k_xl');
-    expect(message).toContain('16,384');
-    expect(message).toContain('40,000');
+    expect(message).toContain((16384).toLocaleString()); // the modal formats for the user's locale
+    expect(message).toContain((40000).toLocaleString());
     expect(message).toMatch(/llama-swap/i);
     expect(message).toMatch(/fit-ctx/i);
 
diff --git a/test/git-clone.test.ts b/test/git-clone.test.ts
index 9b588055..9da829e8 100644
--- a/test/git-clone.test.ts
+++ b/test/git-clone.test.ts
@@ -239,6 +239,14 @@ describe('gitNonInteractiveEnv', () => {
   it("does not override a user's own GIT_SSH_COMMAND", () => {
     expect(gitNonInteractiveEnv({ GIT_SSH_COMMAND: 'ssh -F /custom' }).GIT_SSH_COMMAND).toBe('ssh -F /custom');
   });
+
+  // Issue #568. CI runs in an English locale, so the real-git tests below cannot
+  // catch a revert: only this assertion fails if the pin is dropped.
+  it("pins git's messages to English over the host's locale, since classifyGitFailure() matches English stderr", () => {
+    const env = gitNonInteractiveEnv({ LC_ALL: 'de_DE.UTF-8', LANG: 'de_DE.UTF-8', LANGUAGE: 'de' });
+    expect(env.LC_ALL).toBe('C');
+    expect(env.LANG).toBe('C');
+  });
 });
 
 describe('parseLsRemoteOutput', () => {
diff --git a/test/routes/git-status-routes.test.ts b/test/routes/git-status-routes.test.ts
index b8f24e9d..5b1c6036 100644
--- a/test/routes/git-status-routes.test.ts
+++ b/test/routes/git-status-routes.test.ts
@@ -14,6 +14,8 @@ import { clearGitStatusCache, runGit, type GitRunner } from '../../src/git-works
 
 const ENV = {
   ...process.env,
+  // As the production runner (git-workspace-status.ts): git's not-a-repo message is matched in English.
+  LC_ALL: 'C',
   GIT_AUTHOR_NAME: 'T',
   GIT_AUTHOR_EMAIL: 't@example.com',
   GIT_COMMITTER_NAME: 'T',