diff --git a/src/api.ts b/src/api.ts
index 6d7e7fe..74c8a34 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -246,11 +246,12 @@ export const post = queryWithBody('POST');
 export const put = queryWithBody('PUT');
 export const doDelete = queryWithBody('DELETE');
 
-// Upload deadline: generous for a slow link (1 s/MB on top of a 30 s base,
-// never below 60 s) but bounded, so a stalled connection cannot hang a CI job
-// forever. The bar keeps ticking while bytes flow; the deadline is absolute.
+// Upload deadline: generous for a slow link (5 s/MB, i.e. ~200 KB/s, on top
+// of a 30 s base, never below 60 s) but bounded, so a stalled connection cannot
+// hang a CI job forever. The bar keeps ticking while bytes flow; the deadline
+// is absolute.
 const UPLOAD_TIMEOUT_BASE_MS = 30_000;
-const UPLOAD_TIMEOUT_PER_MB_MS = 1_000;
+const UPLOAD_TIMEOUT_PER_MB_MS = 5_000;
 const UPLOAD_TIMEOUT_MIN_MS = 60_000;
 const UPLOAD_MAX_RETRIES = 1;
 
diff --git a/tests/api.test.ts b/tests/api.test.ts
index cd4185e..01e1761 100644
--- a/tests/api.test.ts
+++ b/tests/api.test.ts
@@ -19,6 +19,7 @@ import {
   replaceSession,
   saveSession,
   setApiToken,
+  uploadTimeoutMs,
 } from '../src/api';
 import * as runtime from '../src/utils/runtime';
 
@@ -289,4 +290,13 @@ describe('api.ts error helpers', () => {
       }),
     ).toBe(true);
   });
+  test('upload deadline allows 5 s per MB on a 30 s base, at least 60 s', () => {
+    const mb = 1048576;
+    expect(uploadTimeoutMs(0)).toBe(60_000);
+    expect(uploadTimeoutMs(5 * mb)).toBe(60_000);
+    expect(uploadTimeoutMs(10 * mb)).toBe(80_000);
+    expect(uploadTimeoutMs(100 * mb)).toBe(530_000);
+    // a partial megabyte counts as a whole one
+    expect(uploadTimeoutMs(100 * mb + 1)).toBe(535_000);
+  });
 });