diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index c22293c1..3e62a1c3 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -1143,6 +1143,28 @@ tp_thumb_detect(struct tp_dispatch *tp, struct tp_touch *t, uint64_t time)
 		}
 	}
 
+	/* If the finger is below the upper thumb line and we have another
+	 * finger in the same area, neither finger is a thumb (unless we've
+	 * already labeled it as such).
+	 */
+	if (t->point.y > tp->thumb.upper_thumb_line &&
+	    tp->nfingers_down > 1) {
+		struct tp_touch *other;
+
+		tp_for_each_touch(tp, other) {
+			if (other->state != TOUCH_BEGIN &&
+			    other->state != TOUCH_UPDATE)
+				continue;
+
+			if (other->point.y > tp->thumb.upper_thumb_line) {
+				t->thumb.state = THUMB_STATE_NO;
+				if (other->thumb.state == THUMB_STATE_MAYBE)
+					other->thumb.state = THUMB_STATE_NO;
+				break;
+			}
+		}
+	}
+
 	/* Note: a thumb at the edge of the touchpad won't trigger the
 	 * threshold, the surface area is usually too small. So we have a
 	 * two-stage detection: pressure and time within the area.
diff --git a/test/litest.c b/test/litest.c
index 1efe6094..458ca793 100644
--- a/test/litest.c
+++ b/test/litest.c
@@ -3570,6 +3570,12 @@ litest_timeout_hysteresis(void)
 	msleep(90);
 }
 
+void
+litest_timeout_thumb(void)
+{
+	msleep(320);
+}
+
 void
 litest_push_event_frame(struct litest_device *dev)
 {
diff --git a/test/litest.h b/test/litest.h
index 7b525c7a..8e6f4447 100644
--- a/test/litest.h
+++ b/test/litest.h
@@ -819,6 +819,9 @@ litest_timeout_touch_arbitration(void);
 void
 litest_timeout_hysteresis(void);
 
+void
+litest_timeout_thumb(void);
+
 void
 litest_push_event_frame(struct litest_device *dev);
 
diff --git a/test/test-touchpad.c b/test/test-touchpad.c
index 00794dbc..8ad695ce 100644
--- a/test/test-touchpad.c
+++ b/test/test-touchpad.c
@@ -5199,6 +5199,76 @@ START_TEST(touchpad_thumb_move_and_tap)
 }
 END_TEST
 
+START_TEST(touchpad_thumb_no_doublethumb)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+
+	litest_disable_tap(dev->libinput_device);
+	litest_enable_clickfinger(dev);
+
+	if (!has_thumb_detect(dev))
+		return;
+
+	litest_drain_events(li);
+
+	litest_touch_down(dev, 0, 50, 99);
+	litest_touch_down(dev, 1, 70, 99);
+	/* move touch to trigger the thumb detection */
+	litest_touch_move(dev, 0, 50, 99.2);
+
+	libinput_dispatch(li);
+	litest_timeout_thumb();
+	libinput_dispatch(li);
+
+	/* move touch to trigger the thumb detection */
+	litest_touch_move(dev, 1, 70, 99.2);
+	libinput_dispatch(li);
+
+	litest_touch_move_two_touches(dev, 50, 99, 70, 99, 0, -20, 10);
+	litest_touch_up(dev, 0);
+	litest_touch_up(dev, 1);
+
+	litest_assert_only_typed_events(li, LIBINPUT_EVENT_POINTER_AXIS);
+}
+END_TEST
+
+START_TEST(touchpad_thumb_no_doublethumb_with_timeout)
+{
+	struct litest_device *dev = litest_current_device();
+	struct libinput *li = dev->libinput;
+
+	litest_disable_tap(dev->libinput_device);
+	litest_enable_clickfinger(dev);
+
+	if (!has_thumb_detect(dev))
+		return;
+
+	litest_drain_events(li);
+
+	litest_touch_down(dev, 0, 50, 99.9);
+	libinput_dispatch(li);
+	litest_timeout_thumb();
+	libinput_dispatch(li);
+	/* Thumbs don't have a timeout handler, so we have to move the thumb
+	 * a bit to trigger. */
+	litest_touch_move(dev, 0, 50, 99.8);
+
+	/* first touch should now be a thumb */
+
+	litest_touch_down(dev, 1, 70, 99.9);
+	libinput_dispatch(li);
+	litest_timeout_thumb();
+	libinput_dispatch(li);
+	litest_touch_move(dev, 1, 70, 99.8);
+	litest_touch_move_two_touches(dev, 50, 99, 70, 99, 0, -20, 10);
+	litest_touch_up(dev, 0);
+	litest_touch_up(dev, 1);
+
+	litest_assert_only_typed_events(li, LIBINPUT_EVENT_POINTER_MOTION);
+}
+END_TEST
+
 START_TEST(touchpad_tool_tripletap_touch_count)
 {
 	struct litest_device *dev = litest_current_device();
@@ -6783,6 +6853,8 @@ TEST_COLLECTION(touchpad)
 	litest_add("touchpad:thumb", touchpad_thumb_tap_hold_2ndfg, LITEST_CLICKPAD, LITEST_SINGLE_TOUCH);
 	litest_add("touchpad:thumb", touchpad_thumb_tap_hold_2ndfg_tap, LITEST_CLICKPAD, LITEST_SINGLE_TOUCH);
 	litest_add("touchpad:thumb", touchpad_thumb_move_and_tap, LITEST_CLICKPAD, LITEST_ANY);
+	litest_add("touchpad:thumb", touchpad_thumb_no_doublethumb, LITEST_CLICKPAD, LITEST_ANY);
+	litest_add("touchpad:thumb", touchpad_thumb_no_doublethumb_with_timeout, LITEST_CLICKPAD, LITEST_ANY);
 
 	litest_add_for_device("touchpad:bugs", touchpad_tool_tripletap_touch_count, LITEST_SYNAPTICS_TOPBUTTONPAD);
 	litest_add_for_device("touchpad:bugs", touchpad_tool_tripletap_touch_count_late, LITEST_SYNAPTICS_TOPBUTTONPAD);