diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
index d73d9826..be0958cf 100644
--- a/include/GLFW/glfw3.h
+++ b/include/GLFW/glfw3.h
@@ -5198,6 +5198,9 @@ GLFWAPI GLFWcharmodsfun glfwSetCharModsCallback(GLFWwindow* window, GLFWcharmods
  *  generated after the focus loss event has been processed, i.e. after the
  *  [window focus callback](@ref glfwSetWindowFocusCallback) has been called.
  *
+ *  The reported `button` value can be higher than `GLFW_MOUSE_BUTTON_LAST` if
+ *  the button is not a [named button](@ref buttons).
+ *
  *  @param[in] window The window whose callback to set.
  *  @param[in] callback The new callback, or `NULL` to remove the currently set
  *  callback.