Index: trunk/test/unit/org/openstreetmap/josm/gui/preferences/server/OverpassServerPanelTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/gui/preferences/server/OverpassServerPanelTest.java	(revision 18403)
+++ trunk/test/unit/org/openstreetmap/josm/gui/preferences/server/OverpassServerPanelTest.java	(revision 18403)
@@ -0,0 +1,50 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.gui.preferences.server;
+
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+
+import java.util.stream.Stream;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.openstreetmap.josm.gui.widgets.HistoryComboBox;
+import org.openstreetmap.josm.io.OverpassDownloadReader;
+import org.openstreetmap.josm.testutils.annotations.BasicPreferences;
+
+/**
+ * Test class for {@link OverpassServerPanel}
+ * @author Taylor Smock
+ * @since 18403
+ */
+@BasicPreferences
+class OverpassServerPanelTest {
+    /**
+     * Non-regression test for <a href="https://josm.openstreetmap.de/ticket/21953">#21953</a>
+     */
+    @ParameterizedTest
+    @ValueSource(strings = {"https://something.example.com/api", "https://something.example.com/api/"})
+    void testOverpassApiServerSaved(final String someRandomUrl) {
+        // We expect the API to have a trailing /
+        final String expected = someRandomUrl.endsWith("/") ? someRandomUrl : someRandomUrl + '/';
+        final OverpassServerPanel panel = new OverpassServerPanel();
+        panel.initFromPreferences();
+        final HistoryComboBox historyComboBox = Stream.of(panel.getComponents()).filter(HistoryComboBox.class::isInstance)
+                .map(HistoryComboBox.class::cast).findFirst().orElseGet(() -> fail("No HistoryComboBox found"));
+        assertEquals(OverpassDownloadReader.OVERPASS_SERVER.get(), historyComboBox.getText());
+        assertAll(OverpassDownloadReader.OVERPASS_SERVER_HISTORY.get().stream()
+                .map(server -> () -> assertNotNull(historyComboBox.getModel().find(server), "Server " + server + " not found")));
+        historyComboBox.setText(someRandomUrl);
+        panel.saveToPreferences();
+        panel.initFromPreferences();
+        assertEquals(OverpassDownloadReader.OVERPASS_SERVER.get(), historyComboBox.getText());
+        assertAll(OverpassDownloadReader.OVERPASS_SERVER_HISTORY.get().stream()
+                .map(server -> () -> assertNotNull(historyComboBox.getModel().find(server), "Server " + server + " not found")));
+        assertEquals(expected, OverpassDownloadReader.OVERPASS_SERVER.get());
+        assertTrue(OverpassDownloadReader.OVERPASS_SERVER_HISTORY.get().contains(expected),
+                String.join(";", OverpassDownloadReader.OVERPASS_SERVER_HISTORY.get()));
+    }
+}