diff --git a/include/wlr/types/wlr_scene.h b/include/wlr/types/wlr_scene.h
index 3b3035d0..8180183f 100644
--- a/include/wlr/types/wlr_scene.h
+++ b/include/wlr/types/wlr_scene.h
@@ -129,11 +129,13 @@ void wlr_scene_node_set_enabled(struct wlr_scene_node *node, bool enabled);
 void wlr_scene_node_set_position(struct wlr_scene_node *node, int x, int y);
 /**
  * Move the node right above the specified sibling.
+ * Asserts that node and sibling are distinct and share the same parent.
  */
 void wlr_scene_node_place_above(struct wlr_scene_node *node,
 	struct wlr_scene_node *sibling);
 /**
  * Move the node right below the specified sibling.
+ * Asserts that node and sibling are distinct and share the same parent.
  */
 void wlr_scene_node_place_below(struct wlr_scene_node *node,
 	struct wlr_scene_node *sibling);
diff --git a/types/scene/wlr_scene.c b/types/scene/wlr_scene.c
index 9ba283ef..2dc29247 100644
--- a/types/scene/wlr_scene.c
+++ b/types/scene/wlr_scene.c
@@ -440,6 +440,7 @@ void wlr_scene_node_set_position(struct wlr_scene_node *node, int x, int y) {
 
 void wlr_scene_node_place_above(struct wlr_scene_node *node,
 		struct wlr_scene_node *sibling) {
+	assert(node != sibling);
 	assert(node->parent == sibling->parent);
 
 	if (node->state.link.prev == &sibling->state.link) {
@@ -455,6 +456,7 @@ void wlr_scene_node_place_above(struct wlr_scene_node *node,
 
 void wlr_scene_node_place_below(struct wlr_scene_node *node,
 		struct wlr_scene_node *sibling) {
+	assert(node != sibling);
 	assert(node->parent == sibling->parent);
 
 	if (node->state.link.next == &sibling->state.link) {