diff --git a/libweston/compositor.c b/libweston/compositor.c
index 303f3aa9..e226f69c 100644
--- a/libweston/compositor.c
+++ b/libweston/compositor.c
@@ -6608,6 +6608,18 @@ weston_output_set_position(struct weston_output *output, int x, int y)
 WL_EXPORT void
 weston_output_move(struct weston_output *output, int x, int y)
 {
+	/* XXX: we should probably perform some sanity checking here
+	 * as we do for weston_output_enable, and allow moves to fail.
+	 *
+	 * However, while a front-end is rearranging outputs it may
+	 * pass through indeterminate states where outputs overlap
+	 * or are discontinuous, and this may be ok as long as no
+	 * input processing or rendering occurs at that time.
+	 *
+	 * Ultimately, we probably need a way to pass complete output
+	 * config atomically to libweston.
+	 */
+
 	output->compositor->output_flow_dirty = true;
 	weston_output_set_position(output, x, y);
 }
@@ -7230,6 +7242,45 @@ weston_output_create_heads_string(struct weston_output *output)
 	return str;
 }
 
+static bool
+weston_outputs_overlap(struct weston_output *a, struct weston_output *b)
+{
+	bool overlap;
+	pixman_region32_t intersection;
+
+	pixman_region32_init(&intersection);
+	pixman_region32_intersect(&intersection, &a->region, &b->region);
+	overlap = pixman_region32_not_empty(&intersection);
+	pixman_region32_fini(&intersection);
+
+	return overlap;
+}
+
+/* This only works if the output region is current!
+ *
+ * That means we shouldn't expect it to return usable results unless
+ * the output is at least undergoing enabling.
+ */
+static bool
+weston_output_placement_ok(struct weston_output *output)
+{
+	struct weston_compositor *c = output->compositor;
+	struct weston_output *iter;
+
+	wl_list_for_each(iter, &c->output_list, link) {
+		if (!iter->enabled)
+			continue;
+
+		if (weston_outputs_overlap(iter, output)) {
+			weston_log("Error: output '%s' overlaps enabled output '%s'.\n",
+				   output->name, iter->name);
+			return false;
+		}
+	}
+
+	return true;
+}
+
 /** Constructs a weston_output object that can be used by the compositor.
  *
  * \param output The weston_output object that needs to be enabled. Must not
@@ -7309,6 +7360,11 @@ weston_output_enable(struct weston_output *output)
 	weston_output_transform_scale_init(output, output->transform, output->scale);
 
 	weston_output_init_geometry(output, output->x, output->y);
+
+	/* At this point we have a valid region so we can check placement. */
+	if (!weston_output_placement_ok(output))
+		return -1;
+
 	weston_output_damage(output);
 
 	wl_list_init(&output->animation_list);