diff --git a/include/wlr/types/wlr_pointer_constraints_v1.h b/include/wlr/types/wlr_pointer_constraints_v1.h
index 98442241..fef8c2e9 100644
--- a/include/wlr/types/wlr_pointer_constraints_v1.h
+++ b/include/wlr/types/wlr_pointer_constraints_v1.h
@@ -1,3 +1,11 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
 #ifndef WLR_TYPES_WLR_POINTER_CONSTRAINTS_V1_H
 #define WLR_TYPES_WLR_POINTER_CONSTRAINTS_V1_H