diff --git a/docs/spec_usdz.rst b/docs/spec_usdz.rst
index 05a73580d3..e306470702 100644
--- a/docs/spec_usdz.rst
+++ b/docs/spec_usdz.rst
@@ -113,6 +113,9 @@ the ability to relax this constraint in the future, but consider it unlikely.
     aggregate an arbitrary composition's worth of usd files into a single file,
     without removing any composition features from the scene.
 
+Additionally, USDZ files must be Zip32 documents. OpenUSD does not support Zip64.
+As such, the total file size of a USDZ must be under 4GB.
+
 Layout
 ------
 
@@ -418,4 +421,4 @@ Version 1.3 - Current Head
 From version 1.2:
 
     * :ref:`Adds AV1 Image (AVIF) file support <spec_usdz_file_types>`. 
-      AVIF is now a supported file type for images/textures.
\ No newline at end of file
+      AVIF is now a supported file type for images/textures.