diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index aaf81c48..7256dbfa 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -15,7 +15,7 @@ jobs:
     strategy:
       matrix:
         host-os: ["ubuntu-latest", "macos-latest", "windows-latest"]
-        python-version: ["3.9", "3.10", "3.11"]
+        python-version: ["3.10", "3.11"]
         numpy-version: ["1.26"]
         pyqt-version: ["5.15"]
         include:
diff --git a/pyxrf/model/lineplot.py b/pyxrf/model/lineplot.py
index 25ff7748..53a8770c 100644
--- a/pyxrf/model/lineplot.py
+++ b/pyxrf/model/lineplot.py
@@ -637,7 +637,8 @@ def plot_vertical_marker(self, *, e_low=None, e_high=None):
         y_v = (-1e30, 1e30)  # This will cover the range of possible values of accumulated counts
 
         if self.line_vertical_marker:
-            self._ax.lines.remove(self.line_vertical_marker)
+            self.line_vertical_marker.remove()
+            # self._ax.lines.remove(self.line_vertical_marker)
             self.line_vertical_marker = None
         if self.vertical_marker_is_visible:
             (self.line_vertical_marker,) = self._ax.plot(x_v, y_v, color="blue")