diff --git a/tests/cli/test_cli_status_bar.py b/tests/cli/test_cli_status_bar.py
index 3edc1e94c80..1899f0dd78e 100644
--- a/tests/cli/test_cli_status_bar.py
+++ b/tests/cli/test_cli_status_bar.py
@@ -400,13 +400,20 @@ class TestCLIStatusBar:
         cli_obj = _make_cli()
         cli_obj._spinner_text = "running tool"
 
-        # <60s path
-        cli_obj._tool_start_time = time.monotonic() - 9.2
-        short = cli_obj._render_spinner_text()
+        # Pin the clock: time.monotonic()'s epoch is arbitrary (often near
+        # boot), so deriving _tool_start_time from the real monotonic clock
+        # made the test fail on hosts where monotonic() < 65.2 — the start
+        # time went negative, the (t0 > 0) guard in _render_spinner_text
+        # dropped the "(elapsed)" suffix entirely, and the split below hit an
+        # IndexError. A fixed clock keeps both elapsed paths deterministic.
+        with patch.object(cli_mod.time, "monotonic", return_value=1000.0):
+            # <60s path
+            cli_obj._tool_start_time = 1000.0 - 9.2
+            short = cli_obj._render_spinner_text()
 
-        # >=60s path
-        cli_obj._tool_start_time = time.monotonic() - 65.2
-        long = cli_obj._render_spinner_text()
+            # >=60s path
+            cli_obj._tool_start_time = 1000.0 - 65.2
+            long = cli_obj._render_spinner_text()
 
         short_elapsed = short.split("(", 1)[1].rstrip(")")
         long_elapsed = long.split("(", 1)[1].rstrip(")")