diff --git a/src/xrt/include/xrt/xrt_limits.h b/src/xrt/include/xrt/xrt_limits.h
index 245d1467c..9c9cfbd6f 100644
--- a/src/xrt/include/xrt/xrt_limits.h
+++ b/src/xrt/include/xrt/xrt_limits.h
@@ -17,8 +17,15 @@
  * @{
  */
 
+/*!
+ * Maximum number of handles sent in one call.
+ */
+#define XRT_MAX_IPC_HANDLES 16
+
 /*!
  * Max swapchain images, artificial limit.
+ *
+ * Must be smaller or the same as XRT_MAX_IPC_HANDLES.
  */
 #define XRT_MAX_SWAPCHAIN_IMAGES 8