diff --git a/include/wlr/types/wlr_xdg_shell.h b/include/wlr/types/wlr_xdg_shell.h
index 410663f7..fa808b60 100644
--- a/include/wlr/types/wlr_xdg_shell.h
+++ b/include/wlr/types/wlr_xdg_shell.h
@@ -40,6 +40,9 @@ struct wlr_xdg_popup {
 	bool committed;
 	struct wlr_xdg_surface *parent;
 	struct wlr_seat *seat;
+
+	// Position of the popup relative to the upper left corner of the window
+	// geometry of the parent surface
 	struct wlr_box geometry;
 
 	struct wl_list grab_link; // wlr_xdg_popup_grab::popups
diff --git a/include/wlr/types/wlr_xdg_shell_v6.h b/include/wlr/types/wlr_xdg_shell_v6.h
index 3bfb97a4..ae3986ed 100644
--- a/include/wlr/types/wlr_xdg_shell_v6.h
+++ b/include/wlr/types/wlr_xdg_shell_v6.h
@@ -40,6 +40,9 @@ struct wlr_xdg_popup_v6 {
 	bool committed;
 	struct wlr_xdg_surface_v6 *parent;
 	struct wlr_seat *seat;
+
+	// Position of the popup relative to the upper left corner of the window
+	// geometry of the parent surface
 	struct wlr_box geometry;
 
 	struct wl_list grab_link; // wlr_xdg_popup_grab_v6::popups