matplotlib
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -451,6 +451,8 @@ def add_label_near(self, x, y, inline=True, inline_spacing=5,
         if transform is None:
             transform = self.axes.transData
         if transform:
+            x = self.axes.convert_xunits(x)
+            y = self.axes.convert_yunits(y)
             x, y = transform.transform((x, y))
 
         idx_level_min, idx_vtx_min, proj = self._find_nearest_contour(

diff --git a/lib/matplotlib/tests/test_datetime.py b/lib/matplotlib/tests/test_datetime.py
@@ -259,11 +259,22 @@ def test_bxp(self):
         ax.xaxis.set_major_formatter(mpl.dates.DateFormatter("%Y-%m-%d"))
         ax.set_title('Box plot with datetime data')
 
-    @pytest.mark.xfail(reason="Test for clabel not written yet")
     @mpl.style.context("default")
     def test_clabel(self):
+        dates = [datetime.datetime(2023, 10, 1) + datetime.timedelta(days=i)
+                for i in range(10)]
+        x = np.arange(-10.0, 5.0, 0.5)
+        X, Y = np.meshgrid(x, dates)
+        Z = np.arange(X.size).reshape(X.shape)
+
         fig, ax = plt.subplots()
-        ax.clabel(...)
+        CS = ax.contour(X, Y, Z)
+        labels = ax.clabel(CS, manual=[(x[0], dates[0])])
+        assert len(labels) == 1
+        assert labels[0].get_text() == '0'
+        x_pos, y_pos = labels[0].get_position()
+        assert x_pos == pytest.approx(-10.0, abs=1e-3)
+        assert y_pos == pytest.approx(mpl.dates.date2num(dates[0]), abs=1e-3)
 
     @mpl.style.context("default")
     def test_contour(self):