diff --git a/libs/nativewindow/include/system/window.h b/libs/nativewindow/include/system/window.h
index 2038632..0bc2b5d 100644
--- a/libs/nativewindow/include/system/window.h
+++ b/libs/nativewindow/include/system/window.h
@@ -1089,7 +1089,10 @@
 /**
  * Retrieves an identifier for the next frame to be queued by this window.
  *
- * \return the next frame id.
+ * Frame ids start at 1 and are incremented on each new frame until the underlying surface changes,
+ * in which case the frame id is reset to 1.
+ *
+ * \return the next frame id (0 being uninitialized).
  */
 static inline uint64_t ANativeWindow_getNextFrameId(ANativeWindow* window) {
     uint64_t value;