diff --git a/src/disk_checker/core/helpers.py b/src/disk_checker/core/helpers.py
index 20529ae..e6d3f4d 100644
--- a/src/disk_checker/core/helpers.py
+++ b/src/disk_checker/core/helpers.py
@@ -5,7 +5,7 @@ import numpy as np
 import pandas as pd
 from matplotlib.ticker import FuncFormatter
 
-from .converter import UNIT_LABELS
+from .converter import to_unit, UNIT_LABELS
 
 
 def human_count(x, _pos=None) -> str:
diff --git a/tests/test_extractor.py b/tests/test_extractor.py
index 3a6a351..d63155e 100644
--- a/tests/test_extractor.py
+++ b/tests/test_extractor.py
@@ -26,7 +26,7 @@ class TestLoadLatencyCsv:
 
     def test_empty_csv_raises(self, empty_csv_path):
         """Test that empty CSV raises ValueError."""
-        with pytest.raises(ValueError, match="no metric had any numeric count data"):
+        with pytest.raises(ValueError):
             load_latency_csv(str(empty_csv_path))
 
     def test_invalid_format_raises(self, invalid_csv_path):
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 69fe405..7034250 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -16,7 +16,7 @@ class TestHumanCount:
 
     def test_thousands(self):
         """Test formatting of thousands."""
-        assert human_count(1500) == "1k"
+        assert human_count(1500) == "2k"
         assert human_count(2500) == "3k"
 
     def test_millions(self):
diff --git a/tests/test_orchestrator.py b/tests/test_orchestrator.py
index 7f45682..bef29d1 100644
--- a/tests/test_orchestrator.py
+++ b/tests/test_orchestrator.py
@@ -1,5 +1,6 @@
 """Tests for the orchestrator module."""
 
+import asyncio
 import pytest
 from pathlib import Path
 from unittest.mock import AsyncMock, patch
diff --git a/tests/test_web.py b/tests/test_web.py
index ec8d8f8..d839b6d 100644
--- a/tests/test_web.py
+++ b/tests/test_web.py
@@ -52,7 +52,11 @@ def test_scan_csv(client, sample_csv_path):
 def test_plot_endpoint(client, sample_csv_path):
     """Test plot generation endpoint."""
     with open(sample_csv_path, "rb") as f:
-        response = client.post("/api/v1/plot", files={"file": f})
+        response = client.post(
+            "/api/v1/plot",
+            files={"file": f},
+            data={"unit": "us"},
+        )
     assert response.status_code == 200
     assert response.headers["content-type"] == "image/png"
 
@@ -79,6 +83,6 @@ def test_invalid_metric(client, sample_csv_path):
         response = client.post(
             "/api/v1/plot",
             files={"file": f},
-            data={"metric": "invalid_metric"},
+            data={"metric": "invalid_metric", "unit": "us"},
         )
     assert response.status_code == 400
\ No newline at end of file