diff --git a/src/__tests__/components/MorphemeBox.test.tsx b/src/__tests__/components/MorphemeBox.test.tsx
index 68ea8ac9..f108d819 100644
--- a/src/__tests__/components/MorphemeBox.test.tsx
+++ b/src/__tests__/components/MorphemeBox.test.tsx
@@ -3,7 +3,7 @@
 /// <reference types="@testing-library/jest-dom" />
 
 import { useLocalizedStrings } from '@papi/frontend/react';
-import { render, screen } from '@testing-library/react';
+import { fireEvent, render, screen } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import type { MorphemeAnalysis, Token } from 'interlinearizer';
 import * as AnalysisStore from '../../components/AnalysisStore';
@@ -118,6 +118,36 @@ describe('MorphemeBox', () => {
     expect(onEditBreakdown).toHaveBeenCalledTimes(1);
   });
 
+  it('calls onEditBreakdown when a non-first form cell is clicked', async () => {
+    // Non-first cells are spans, not buttons, so they need their own coverage.
+    const onEditBreakdown = jest.fn();
+    renderBox({ onEditBreakdown });
+    await userEvent.click(screen.getByText('-lo'));
+    expect(onEditBreakdown).toHaveBeenCalledTimes(1);
+  });
+
+  it('stops a non-first form cell mousedown from bubbling to an ancestor handler', () => {
+    // Regression test: an ancestor onMouseDown (e.g. TokenChip's label) would otherwise focus the
+    // gloss input, since a span (unlike a button) doesn't match its input/button guard.
+    const onAncestorMouseDown = jest.fn();
+    render(
+      // Stand-in for an ancestor React handler, not real UI.
+      // eslint-disable-next-line jsx-a11y/no-static-element-interactions
+      <div onMouseDown={onAncestorMouseDown}>
+        <MorphemeBox
+          analysisLanguage="en"
+          disabled={false}
+          morphemes={MORPHEMES}
+          onEditBreakdown={jest.fn()}
+          popoverOpen={false}
+          token={WORD_TOKEN}
+        />
+      </div>,
+    );
+    fireEvent.mouseDown(screen.getByText('-lo'));
+    expect(onAncestorMouseDown).not.toHaveBeenCalled();
+  });
+
   it('does not call onEditBreakdown when disabled', async () => {
     const onEditBreakdown = jest.fn();
     renderBox({ disabled: true, onEditBreakdown });
diff --git a/src/components/MorphemeBox.tsx b/src/components/MorphemeBox.tsx
index 059d107c..789209b6 100644
--- a/src/components/MorphemeBox.tsx
+++ b/src/components/MorphemeBox.tsx
@@ -118,8 +118,11 @@ export function MorphemeBox({
               key={m.id}
               aria-hidden="true"
               className={formClassName}
-              style={formStyle}
               onClick={handleClick}
+              // Not a button, so stop mousedown from bubbling to TokenChip's label handler (which
+              // would otherwise focus the gloss input).
+              onMouseDown={(e) => e.stopPropagation()}
+              style={formStyle}
             >
               {m.form}
             </span>
diff --git a/src/components/TokenChip.tsx b/src/components/TokenChip.tsx
index abea5929..0ec99ad8 100644
--- a/src/components/TokenChip.tsx
+++ b/src/components/TokenChip.tsx
@@ -167,8 +167,10 @@ export function TokenChip({
    * The input is looked up by id rather than `querySelector('input')` because the morpheme gloss
    * inputs precede it inside the label when morphology is shown. A mouse-down on any input is left
    * to that input's own handling ({@link handleMouseDown} for the gloss input, which bubbles here
-   * after already handling it); a mouse-down on a morpheme form cell or the unanalyzed "define"
-   * trigger (all `button`s) is left to that button's own click handler, which opens the popover.
+   * after already handling it); a mouse-down on the first morpheme form cell or the unanalyzed
+   * "define" trigger (both real `button`s) is left to that button's own click handler. The
+   * remaining morpheme form cells are `span`s that stop their own mousedown from bubbling here
+   * instead (see {@link MorphemeBox}).
    *
    * @param e - The label's mouse-down event.
    */